{"id":17916,"date":"2025-11-10T11:24:36","date_gmt":"2025-11-10T11:24:36","guid":{"rendered":"https:\/\/mcqsadda.com\/?p=17916"},"modified":"2025-12-29T04:24:52","modified_gmt":"2025-12-29T04:24:52","slug":"database-concepts-100-mcqs-with-answer-and-explanation","status":"publish","type":"post","link":"https:\/\/mcqsadda.com\/index.php\/2025\/11\/10\/database-concepts-100-mcqs-with-answer-and-explanation\/","title":{"rendered":"Database Concepts 100 MCQs With Answer and Explanation"},"content":{"rendered":"\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">1. A database is:<\/mark><\/strong><br>A) A collection of files<br>B) A collection of interrelated data<br>C) A programming language<br>D) An operating system<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  A database is an organized collection of related data that can be easily accessed, managed, and updated.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">2. Which of the following is NOT a DBMS?<\/mark><\/strong><br>A) Oracle<br>B) MySQL<br>C) MS Excel<br>D) PostgreSQL<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: C <\/b><BR>\n<b>Explanation:<\/b>  Excel is a spreadsheet software, not a database management system (DBMS).\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">3. DBMS stands for:<\/mark><\/strong><br>A) Database Management System<br>B) Data Backup Management System<br>C) Digital Base Management Software<br>D) Data Binary Management System<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: A <\/b><BR>\n<b>Explanation:<\/b>  DBMS manages and organizes data in databases.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">4. Which of the following is an example of RDBMS?<\/mark><\/strong><br>A) MySQL<br>B) MongoDB<br>C) Redis<br>D) Neo4j<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: A <\/b><BR>\n<b>Explanation:<\/b>  MySQL is a relational DBMS where data is stored in tables with rows and columns.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">5. The smallest unit of data in a database is:<\/mark><\/strong><br>A) File<br>B) Record<br>C) Field<br>D) Bit<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: C <\/b><BR>\n<b>Explanation:<\/b>  A field represents a single piece of data (e.g., name, age).\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">6. A table in a relational database is also known as:<\/mark><\/strong><br>A) File<br>B) Relation<br>C) Record<br>D) Schema<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  In relational databases, tables are also called relations.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">7. Which key uniquely identifies each record in a table?<\/mark><\/strong><br>A) Foreign key<br>B) Primary key<br>C) Candidate key<br>D) Alternate key<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  A primary key is a unique identifier for each row in a table.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">8. Which of the following is a type of DBMS?<\/mark><\/strong><br>A) Hierarchical<br>B) Network<br>C) Relational<br>D) All of the above<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: D <\/b><BR>\n<b>Explanation:<\/b>   DBMS can be hierarchical, network, relational, or object-oriented.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">9. SQL stands for:<\/mark><\/strong><br>A) Structured Query Language<br>B) Standard Question Language<br>C) Simple Query Language<br>D) Sequential Query Language<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: A <\/b><BR>\n<b>Explanation:<\/b>  SQL is the standard language to interact with relational databases.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">10. Which SQL command is used to retrieve data from a database?<\/mark><\/strong><br>A) SELECT<br>B) UPDATE<br>C) INSERT<br>D) DELETE<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: A <\/b><BR>\n<b>Explanation:<\/b>  SELECT is used to retrieve data from one or more tables.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">11. Which SQL command is used to remove all rows from a table but keep the structure?<\/mark><\/strong><br>A) DROP<br>B) TRUNCATE<br>C) DELETE<br>D) CLEAR<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b> TRUNCATE removes all rows quickly but retains the table structure.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">12. In SQL, which clause is used to filter records?<\/mark><\/strong><br>A) WHERE<br>B) GROUP BY<br>C) ORDER BY<br>D) HAVING<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: A  <\/b><BR>\n<b>Explanation:<\/b>   WHERE filters records based on conditions.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">13. Which normal form removes partial dependency?<\/mark><\/strong><br>A) 1NF<br>B) 2NF<br>C) 3NF<br>D) BCNF<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  2NF eliminates partial dependency in relational schema.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">14. In relational database terminology, a row is called:<\/mark><\/strong><br>A) Field<br>B) Record<br>C) Attribute<br>D) Schema<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  Each row in a table is called a record (or tuple).\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">15. Which type of key is used to link two tables?<\/mark><\/strong><br>A) Primary key<br>B) Foreign key<br>C) Candidate key<br>D) Alternate key<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  Foreign keys maintain referential integrity between related tables.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">16. Which of these is NOT a DML command?<\/mark><\/strong><br>A) INSERT<br>B) DELETE<br>C) UPDATE<br>D) CREATE<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: D  <\/b><BR>\n<b>Explanation:<\/b>  CREATE is a DDL command, while DML commands modify data.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">17. Which of the following is a NoSQL database?<\/mark><\/strong><br>A) Oracle<br>B) MySQL<br>C) MongoDB<br>D) SQL Server<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: C <\/b><BR>\n<b>Explanation:<\/b>  MongoDB is a document-oriented NoSQL database.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">18. ACID properties in DBMS ensure:<\/mark><\/strong><br>A) Database security<br>B) Database transactions reliability<br>C) Faster queries<br>D) Backup creation<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  ACID (Atomicity, Consistency, Isolation, Durability) ensures reliable transactions.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">19. The command to remove a database in SQL is:<\/mark><\/strong><br>A) DROP DATABASE<br>B) DELETE DATABASE<br>C) REMOVE DATABASE<br>D) ERASE DATABASE<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: A <\/b><BR>\n<b>Explanation:<\/b>  DROP DATABASE permanently removes a database.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">20. The command UPDATE Students SET Marks = 90 WHERE ID = 1; does what?<\/mark><\/strong><br>A) Deletes record<br>B) Updates marks for student with ID 1<br>C) Creates a new record<br>D) Selects record<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b> UPDATE modifies existing data in a table.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>21. Which of the following prevents unauthorized access to data?<\/strong><br><\/mark>A) Backup<br>B) Encryption<br>C) Normalization<br>D) Indexing<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b> Encryption secures data from unauthorized access.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>22. Which SQL keyword is used to arrange results in ascending or descending order?<\/strong><br><\/mark>A) SORT<br>B) ORDER BY<br>C) GROUP BY<br>D) ALIGN BY<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  ORDER BY sorts query results based on columns.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>23. Which command is used to remove a table completely?<\/strong><br><\/mark>A) DROP TABLE<br>B) TRUNCATE TABLE<br>C) DELETE TABLE<br>D) ERASE TABLE<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: A <\/b><BR>\n<b>Explanation:<\/b>  DROP TABLE deletes the table and its structure.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>24. Which SQL clause is used to group rows based on common values?<\/strong><br><\/mark>A) GROUP BY<br>B) ORDER BY<br>C) WHERE<br>D) JOIN<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: A <\/b><BR>\n<b>Explanation:<\/b>  GROUP BY groups records by common field values for aggregation.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>25. Which database model represents data in tree-like structure?<\/strong><br><\/mark>A) Network Model<br>B) Hierarchical Model<br>C) Relational Model<br>D) Object-Oriented Model<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  Hierarchical model organizes data in tree-like parent-child relationships.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>26. Which of the following is a DDL command?<\/strong><br><\/mark>A) INSERT<br>B) UPDATE<br>C) CREATE<br>D) DELETE<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: C  <\/b><BR>\n<b>Explanation:<\/b>  DDL (Data Definition Language) commands define structures; CREATE is used to create tables, views, etc.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>27. Which of the following is NOT a property of a transaction in DBMS?<\/strong><br><\/mark>A) Atomicity<br>B) Consistency<br>C) Isolation<br>D) Flexibility<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: D  <\/b><BR>\n<b>Explanation:<\/b>  The four transaction properties are ACID \u2013 Atomicity, Consistency, Isolation, Durability.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>28. Which normal form eliminates transitive dependency?<\/strong><br><\/mark>A) 1NF<br>B) 2NF<br>C) 3NF<br>D) BCNF<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: C  <\/b><BR>\n<b>Explanation:<\/b>  3NF ensures no transitive dependency between non-key attributes.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>29. Which SQL command is used to add a new record into a table?<\/strong><br><\/mark>A) ADD<br>B) INSERT<br>C) CREATE<br>D) APPEND<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  INSERT adds new rows of data into a table.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>30. Which command is used to remove specific rows from a table?<\/strong><br><\/mark>A) DROP<br>B) TRUNCATE<br>C) DELETE<br>D) REMOVE<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: C  <\/b><BR>\n<b>Explanation:<\/b>  DELETE removes specified rows, but table structure remains.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>31. Which of the following is NOT a constraint in SQL?<\/strong><br><\/mark>A) PRIMARY KEY<br>B) FOREIGN KEY<br>C) UNIQUE<br>D) UPDATE<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: D  <\/b><BR>\n<b>Explanation:<\/b>  UPDATE is a DML command, not a constraint.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>32. Which SQL keyword is used to combine rows from two or more tables based on related columns?<\/strong><br><\/mark>A) GROUP<br>B) JOIN<br>C) UNION<br>D) LINK<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  JOINs are used to retrieve data from multiple related tables.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>33. Which SQL command is used to rename a table?<\/strong><br><\/mark>A) RENAME<br>B) ALTER<br>C) UPDATE<br>D) CHANGE<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: A  <\/b><BR>\n<b>Explanation:<\/b>  RENAME TABLE old_name TO new_name changes the name of a table.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>34. Which type of join returns all rows when there is a match in either table?<\/strong><br><\/mark>A) INNER JOIN<br>B) LEFT JOIN<br>C) RIGHT JOIN<br>D) FULL OUTER JOIN<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: D <\/b><BR>\n<b>Explanation:<\/b>  FULL OUTER JOIN returns all records when there is a match in either table.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>35. Which clause is used with aggregate functions like SUM, AVG, COUNT?<\/strong><br><\/mark>A) ORDER BY<br>B) WHERE<br>C) GROUP BY<br>D) HAVING<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: C  <\/b><BR>\n<b>Explanation:<\/b>  GROUP BY groups records for aggregate operations.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>36. Which clause is used to filter aggregated data?<\/strong><br><\/mark>A) WHERE<br>B) HAVING<br>C) ORDER BY<br>D) LIMIT<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  HAVING filters results after aggregation (WHERE filters before aggregation).\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>37. Which of the following is NOT an aggregate function in SQL?<\/strong><br><\/mark>A) COUNT()<br>B) SUM()<br>C) MAX()<br>D) UPDATE()<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: D <\/b><BR>\n<b>Explanation:<\/b>  UPDATE is a DML command, not an aggregate function.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>38. Which SQL operator is used to search for a pattern in a column?<\/strong><br><\/mark>A) BETWEEN<br>B) LIKE<br>C) IN<br>D) EXISTS<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  LIKE operator uses wildcards (%, _) to search for patterns.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>39. Which operator is used to check for NULL values in SQL?<\/strong><br><\/mark>A) = NULL<br>B) IS NULL<br>C) == NULL<br>D) NULL<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>   IS NULL is used to check for NULL values.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>40. Which of the following is NOT a valid SQL data type?<\/strong><br><\/mark>A) INTEGER<br>B) VARCHAR<br>C) FLOAT<br>D) ARRAY<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: D <\/b><BR>\n<b>Explanation:<\/b>   SQL does not have ARRAY as a standard data type.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>41. Which index type updates automatically when data changes in the table?<\/strong><br><\/mark>A) Static index<br>B) Dynamic index<br>C) Clustered index<br>D) Bitmap index<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: C <\/b><BR>\n<b>Explanation:<\/b>  Clustered index maintains physical order of rows and updates automatically with changes.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>42. Which of the following is used to uniquely identify rows in a table?<\/strong><br><\/mark>A) Primary Key<br>B) Index<br>C) View<br>D) Trigger<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: A <\/b><BR>\n<b>Explanation:<\/b>  Primary key uniquely identifies each row.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>43. Which of the following is NOT a characteristic of DBMS?<\/strong><br><\/mark>A) Data Redundancy<br>B) Data Sharing<br>C) Data Integrity<br>D) Data Security<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: A <\/b><BR>\n<b>Explanation:<\/b>   DBMS reduces redundancy, while ensuring sharing, integrity, and security.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>44. Which language is used to define the structure of a database?<\/strong><br><\/mark>A) DML<br>B) DDL<br>C) DCL<br>D) TCL<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  Data Definition Language (DDL) defines database schema and structure.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>45. Which language is used to control access to data in DBMS?<\/strong><br><\/mark>A) DML<br>B) DDL<br>C) DCL<br>D) TCL<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: C <\/b><BR>\n<b>Explanation:<\/b>  Data Control Language (DCL) includes GRANT and REVOKE for access control.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>46. Which language is used to manipulate data in DBMS?<\/strong><br><\/mark>A) DML<br>B) DDL<br>C) DCL<br>D) HTML<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: A  <\/b><BR>\n<b>Explanation:<\/b>  Data Manipulation Language (DML) includes INSERT, UPDATE, DELETE, SELECT.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">47. Which language is used to manage database transactions?<\/mark><\/strong><br>A) TCL<br>B) DDL<br>C) DCL<br>D) DML<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: A <\/b><BR>\n<b>Explanation:<\/b> Transaction Control Language (TCL) includes COMMIT, ROLLBACK, SAVEPOINT.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>48. Which SQL clause limits the number of rows returned?<\/strong><br><\/mark>A) WHERE<br>B) LIMIT<br>C) HAVING<br>D) TOP<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  LIMIT restricts the number of rows (in SQL Server, TOP is used).\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>49. Which of the following is an example of an object-oriented database?<\/strong><br><\/mark>A) Oracle<br>B) MongoDB<br>C) PostgreSQL with object features<br>D) MySQL<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: C <\/b><BR>\n<b>Explanation:<\/b>  PostgreSQL supports object-relational features, making it object-oriented.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>50. Which database model allows many-to-many relationships with links?<\/strong><br><\/mark>A) Hierarchical<br>B) Network<br>C) Relational<br>D) Object-oriented<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  Network model allows many-to-many relationships using sets and pointers.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>51. In SQL, which keyword is used to remove duplicate values from results?<\/strong><br><\/mark>A) DISTINCT<br>B) UNIQUE<br>C) FILTER<br>D) CLEAN<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: A  <\/b><BR>\n<b>Explanation:<\/b>  DISTINCT eliminates duplicate rows from the result set.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>52. Which of the following is used to enforce data integrity?<\/strong><br><\/mark>A) Keys<br>B) Indexes<br>C) Views<br>D) Reports<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: A  <\/b><BR>\n<b>Explanation:<\/b>  Keys (Primary, Foreign, Unique) enforce entity and referential integrity.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>53. What does a foreign key ensure?<\/strong><br><\/mark>A) Uniqueness of data<br>B) No NULL values<br>C) Referential integrity between tables<br>D) Fast searching<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: C <\/b><BR>\n<b>Explanation:<\/b>  Foreign key ensures consistency between related tables.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>54. Which of the following is NOT a valid SQL constraint?<\/strong><br><\/mark>A) CHECK<br>B) NOT NULL<br>C) INDEX<br>D) DEFAULT<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: C <\/b><BR>\n<b>Explanation:<\/b>  Index improves search speed, but it is not a constraint.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>55. Which command undoes changes in a transaction?<\/strong><br><\/mark>A) SAVEPOINT<br>B) COMMIT<br>C) ROLLBACK<br>D) GRANT<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: C <\/b><BR>\n<b>Explanation:<\/b>  ROLLBACK cancels a transaction and restores the previous state.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>56. Which command permanently saves changes in a database?<\/strong><br><\/mark>A) SAVEPOINT<br>B) COMMIT<br>C) ROLLBACK<br>D) LOCK<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  COMMIT makes changes permanent.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>57. Which command is used to grant permissions to a user?<\/strong><br><\/mark>A) REVOKE<br>B) GRANT<br>C) PERMIT<br>D) ALLOW<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  GRANT assigns privileges to users in a database.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>58. Which command removes permissions from a user?<\/strong><br><\/mark>A) REMOVE<br>B) REVOKE<br>C) DELETE<br>D) DENY<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  REVOKE takes away privileges granted earlier.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>59. Which index type is most commonly used in relational databases?<\/strong><br><\/mark>A) Clustered Index<br>B) Bitmap Index<br>C) Hash Index<br>D) Inverted Index<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: A  <\/b><BR>\n<b>Explanation:<\/b>  Clustered index defines the physical order of rows in a table.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>60. A stored procedure in SQL is:<\/strong><br><\/mark>A) A compiled set of SQL statements<br>B) A table with triggers<br>C) A temporary table<br>D) A view<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: A <\/b><BR>\n<b>Explanation:<\/b>  Stored procedures are reusable, precompiled blocks of SQL code.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>61. Which SQL object is used to generate values automatically?<\/strong><br><\/mark>A) Trigger<br>B) Sequence<br>C) Procedure<br>D) Function<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>   A sequence generates auto-incrementing numeric values.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>62. A trigger in DBMS is:<\/strong><br><\/mark>A) A predefined action executed automatically<br>B) A foreign key<br>C) A procedure that runs manually<br>D) A type of schema<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: A  <\/b><BR>\n<b>Explanation:<\/b>  Triggers execute automatically when certain events (INSERT, UPDATE, DELETE) occur.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>63. Which SQL keyword is used to join multiple queries\u2019 results together?<\/strong><br><\/mark>A) JOIN<br>B) UNION<br>C) INTERSECT<br>D) MERGE<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  UNION combines results from multiple SELECT queries (removing duplicates).\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>64. Which SQL operator returns rows common to both queries?<\/strong><br><\/mark>A) UNION<br>B) UNION ALL<br>C) INTERSECT<br>D) EXCEPT<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: C <\/b><BR>\n<b>Explanation:<\/b>   INTERSECT returns only the common records from two queries.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>65. Which SQL operator returns rows from first query but not from the second?<\/strong><br><\/mark>A) UNION<br>B) INTERSECT<br>C) EXCEPT<br>D) DIFFERENCE<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: C  <\/b><BR>\n<b>Explanation:<\/b>  EXCEPT returns records present in the first query but not in the second.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>66. Which of the following is a view in SQL?<\/strong><br><\/mark>A) A virtual table<br>B) A stored file<br>C) A data copy<br>D) A transaction<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: A  <\/b><BR>\n<b>Explanation:<\/b>   A view is a virtual table created from SELECT queries, storing no data itself.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>67. Which of the following statements about views is TRUE?<\/strong><br><\/mark>A) Views can store data physically<br>B) Views are always updatable<br>C) Views are stored queries<br>D) Views are faster than tables<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: C <\/b><BR>\n<b>Explanation:<\/b>  Views act as saved SQL queries providing virtual access to data.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>68. Which of the following is a type of database architecture?<\/strong><br><\/mark>A) 1-tier<br>B) 2-tier<br>C) 3-tier<br>D) All of the above<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: D  <\/b><BR>\n<b>Explanation:<\/b>  Database architectures can be 1-tier, 2-tier, or 3-tier depending on layers.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>69. In a 3-tier architecture, the middle layer is called:<\/strong><br><\/mark>A) Client layer<br>B) Application layer<br>C) Database layer<br>D) Server layer<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  3-tier architecture consists of client, application, and database layers.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">70. Which is the fastest searching mechanism in DBMS?<br><\/mark><\/strong>A) Primary key search<br>B) Sequential search<br>C) Index search<br>D) Nested query<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: C <\/b><BR>\n<b>Explanation:<\/b>  Indexes improve search speed significantly over sequential scans.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>71. Which of the following is NOT an advantage of DBMS?<\/strong><br><\/mark>A) Data sharing<br>B) Data integrity<br>C) Data redundancy<br>D) Data security<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: C <\/b><BR>\n<b>Explanation:<\/b>  DBMS reduces redundancy instead of encouraging it.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">72. A deadlock occurs when:<br><\/mark><\/strong>A) Two transactions wait for each other\u2019s resources<br>B) System crashes<br>C) Database gets corrupted<br>D) Memory is full<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: A  <\/b><BR>\n<b>Explanation:<\/b>  Deadlock is a state where two or more transactions cannot proceed due to circular waiting.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>73. Which of the following is used to prevent deadlocks?<\/strong><br><\/mark>A) Locks<br>B) Timeouts<br>C) Priority scheduling<br>D) All of the above<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: D  <\/b><BR>\n<b>Explanation:<\/b>  Deadlocks can be prevented using locks, timeouts, or priority schemes.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>74. Which concurrency control technique ensures serializability?<\/strong><br><\/mark>A) Locking<br>B) Timestamp ordering<br>C) Validation<br>D) All of the above<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: D  <\/b><BR>\n<b>Explanation:<\/b>   Concurrency control ensures serializable execution using these techniques.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>75. Which backup type stores only changes since the last full backup?<\/strong><br><\/mark>A) Full backup<br>B) Incremental backup<br>C) Differential backup<br>D) Cold backup<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  Incremental backup saves space by storing only modified data since the last full backup.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>76. Which of the following is a type of database model?<\/strong><br><\/mark>A) Hierarchical<br>B) Network<br>C) Relational<br>D) All of the above<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: D <\/b><BR>\n<b>Explanation:<\/b>  Different DBMSs use hierarchical, network, or relational models to organize data.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>77. Which of these is the most widely used database model today?<\/strong><br><\/mark>A) Hierarchical<br>B) Relational<br>C) Network<br>D) Object-oriented<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B  <\/b><BR>\n<b>Explanation:<\/b>  The relational model (tables\/relations) is the standard in modern DBMSs.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>78. Which normal form removes partial dependency?<\/strong><br><\/mark>A) 1NF<br>B) 2NF<br>C) 3NF<br>D) BCNF<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  2NF ensures no partial dependency of non-prime attributes on a part of a candidate key.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>79. Which normal form removes transitive dependency?<\/strong><br><\/mark>A) 1NF<br>B) 2NF<br>C) 3NF<br>D) 4NF<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: C <\/b><BR>\n<b>Explanation:<\/b>  3NF eliminates transitive dependency, improving data integrity.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>80. Which is the highest level of normalization typically used in practice?<\/strong><br><\/mark>A) 3NF<br>B) BCNF<br>C) 4NF<br>D) 5NF<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  Boyce-Codd Normal Form (BCNF) is often considered sufficient for practical databases.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>81. Denormalization in DBMS means:<\/strong><br><\/mark>A) Splitting tables<br>B) Combining tables for faster queries<br>C) Normalizing again<br>D) Removing redundancy completely<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  Denormalization improves query speed by allowing some redundancy.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>82. Which is a disadvantage of normalization?<\/strong><br><\/mark>A) Reduces redundancy<br>B) Reduces anomalies<br>C) Slower query performance<br>D) Improves data integrity<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: C <\/b><BR>\n<b>Explanation:<\/b>   Excessive normalization may slow queries due to multiple joins.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>83. Data warehouse mainly stores:<\/strong><br><\/mark>A) Transactional data<br>B) Historical data<br>C) Temporary data<br>D) Random data<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>   Data warehouses are designed to store and analyze historical data for decision-making.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>84. OLTP systems are mainly used for:<\/strong><br><\/mark>A) Day-to-day transaction processing<br>B) Data analysis<br>C) Historical reporting<br>D) Forecasting<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: A <\/b><BR>\n<b>Explanation:<\/b>  OLTP handles real-time operational transactions (like banking, bookings).\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>85. OLAP systems are mainly used for:<\/strong><br><\/mark>A) Transaction processing<br>B) Data analysis and reporting<br>C) Data redundancy<br>D) File storage<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  OLAP is used for analytical queries, reporting, and decision-making.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>86. Which type of key uniquely identifies a record in a table?<\/strong><br><\/mark>A) Foreign key<br>B) Primary key<br>C) Composite key<br>D) Super key<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  The primary key ensures uniqueness and non-null values for each record.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>87. Which of the following is a candidate key?<\/strong><br><\/mark>A) Any attribute that can uniquely identify a row<br>B) A redundant key<br>C) Only foreign keys<br>D) A partial key<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: A  <\/b><BR>\n<b>Explanation:<\/b>  Candidate keys are attributes eligible to be chosen as a primary key.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>88. Which SQL statement is used to modify existing data in a table?<\/strong><br><\/mark>A) UPDATE<br>B) ALTER<br>C) MODIFY<br>D) CHANGE<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: A  <\/b><BR>\n<b>Explanation:<\/b>  UPDATE modifies existing rows in a table.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>89. Which SQL command is used to remove all rows but keep the structure of a table?<\/strong><br><\/mark>A) DROP<br>B) TRUNCATE<br>C) DELETE<br>D) REMOVE<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  TRUNCATE removes all rows quickly but retains the table schema.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>90. Which SQL clause is used to filter rows after grouping?<\/strong><br><\/mark>A) WHERE<br>B) HAVING<br>C) GROUP BY<br>D) ORDER BY<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  HAVING applies conditions to grouped rows, unlike WHERE which filters before grouping.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\"><strong>91. Which SQL function returns the number of rows?<\/strong><br><\/mark>A) COUNT()<br>B) SUM()<br>C) MAX()<br>D) AVG()<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: A  <\/b><BR>\n<b>Explanation:<\/b>  COUNT() returns the total number of rows that match a query condition.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">92. Which SQL keyword sorts query results?<\/mark><\/strong><br>A) ORDER BY<br>B) SORT BY<br>C) GROUP BY<br>D) ARRANGE<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: A  <\/b><BR>\n<b>Explanation:<\/b>  ORDER BY sorts rows in ascending or descending order.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">93. Which SQL keyword returns unique values only?<\/mark><\/strong><br>A) UNIQUE<br>B) DISTINCT<br>C) FILTER<br>D) ONLY<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  DISTINCT removes duplicates in the output.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">94. Which key in a relational database can accept NULL values?<\/mark><\/strong><br>A) Primary key<br>B) Candidate key<br>C) Foreign key<br>D) Super key<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: C  <\/b><BR>\n<b>Explanation:<\/b>   Foreign keys can have NULL values if no relationship exists.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">95. What does ACID stand for in DBMS?<\/mark><\/strong><br>A) Accuracy, Consistency, Isolation, Durability<br>B) Atomicity, Consistency, Isolation, Durability<br>C) Atomicity, Correctness, Independence, Durability<br>D) All Changes, Integrity, Data<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  ACID properties ensure reliable database transactions.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">96. Which of the following ensures atomicity in transactions?<\/mark><\/strong><br>A) Log files<br>B) Commit &amp; Rollback<br>C) Checkpoints<br>D) Deadlock handling<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  COMMIT confirms atomic actions, ROLLBACK cancels uncompleted ones.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">97. A database index mainly improves:<\/mark><\/strong><br>A) Data integrity<br>B) Security<br>C) Query performance<br>D) Storage size<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: C <\/b><BR>\n<b>Explanation:<\/b>   Indexing speeds up searches at the cost of extra storage.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">98. Which of the following is an example of a NoSQL database?<\/mark><\/strong><br>A) Oracle<br>B) MySQL<br>C) MongoDB<br>D) MS Access<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: C  <\/b><BR>\n<b>Explanation:<\/b>  MongoDB is a NoSQL database that stores data in JSON-like format.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">99. Which of the following databases is used in Android mobile applications?<\/mark><\/strong><br>A) MySQL<br>B) SQLite<br>C) PostgreSQL<br>D) Oracle<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: B <\/b><BR>\n<b>Explanation:<\/b>  SQLite is lightweight and embedded, widely used in mobile applications.\n <\/p>\n<\/div>\n\n\n\n<p class=\"has-large-font-size\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-luminous-vivid-orange-color\">100. Which of the following best describes a distributed database?<\/mark><\/strong><br>A) A database stored on a single server<br>B) A database copied for backup<br>C) A database spread across multiple locations<br>D) A database without indexes<\/p>\n\n\n\n<button class=\"acc\">Show Answer<\/button>\n<div class=\"pnl\">\n  <p style=\"font-size: 22px;\"><b> Answer: C  <\/b><BR>\n<b>Explanation:<\/b>  Distributed databases store and manage data across multiple physical locations but appear as a single system.\n <\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>1. A database is:A) A collection of filesB) A collection of interrelated dataC) A programming languageD) An operating system Show Answer Answer: B Explanation: A database is an organized collection of related data that can be easily accessed, managed, and updated. 2. Which of the following is NOT a DBMS?A) OracleB) MySQLC) MS ExcelD) PostgreSQL<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":"[]"},"categories":[1],"tags":[],"class_list":{"0":"post-17916","1":"post","2":"type-post","3":"status-publish","4":"format-standard","6":"category-blog"},"_links":{"self":[{"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/posts\/17916","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/comments?post=17916"}],"version-history":[{"count":104,"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/posts\/17916\/revisions"}],"predecessor-version":[{"id":31120,"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/posts\/17916\/revisions\/31120"}],"wp:attachment":[{"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/media?parent=17916"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/categories?post=17916"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/tags?post=17916"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}