Top 50 DB2 Interview Questions and Answers PDF Download

Top 50 DB2 Interview Questions and Answers

1. What is DB2?

   DB2 is a Relational Database Management System (RDBMS) developed by IBM. It is designed to store, analyze, and retrieve large amounts of structured data efficiently.

2. What are the main features of DB2?

   The main features of DB2 are:

   • Support for SQL (Structured Query Language)
   • ACID-compliant transactions
   • Scalability and performance optimization
   • Security and data integrity
   • Data replication and high availability

3. What are the different editions of DB2?

   DB2 is available in different editions, including:

   • DB2 Express-C: The free community edition
   • DB2 Express: The entry-level edition
   • DB2 Workgroup Server Edition: The mid-range edition
   • DB2 Enterprise Server Edition: The advanced edition

4. What is a tablespace in DB2?

   A tablespace in DB2 is a storage area that contains tables, indexes, and other database objects. It is used to organize and allocate storage space for these objects.

5. What is a bufferpool in DB2?

   A bufferpool in DB2 is a cache that holds data pages in memory to improve database performance. It reduces the need for disk I/O by keeping frequently accessed data in memory.

6. What is a data page in DB2?

   A data page in DB2 is the basic unit of storage in the database. It contains rows of data from one or more tables or indexes.

7. What is a DB2 package?

   A DB2 package is a compiled version of a DB2 program that contains executable code. It is stored in the database and can be executed by the DB2 engine.

8. What is a cursor in DB2?

   A cursor in DB2 is a database object used to retrieve and manipulate data row by row. It allows you to process query results one row at a time.

9. What is a stored procedure in DB2?

   A stored procedure in DB2 is a set of SQL and procedural statements that are stored and executed on the database server. It encapsulates business logic and can be called by applications.

10. What is a trigger in DB2?

    A trigger in DB2 is a database object that is automatically executed in response to a specific event, such as an INSERT, UPDATE, or DELETE operation on a table.

11. What is the difference between a primary key and a unique constraint in DB2?

    In DB2, a primary key is a set of one or more columns that uniquely identifies a row in a table. It enforces the constraint of uniqueness and does not allow NULL values. On the other hand, a unique constraint also enforces the constraint of uniqueness but allows NULL values.

12. What is a foreign key in DB2?

    A foreign key in DB2 is a column or a set of columns that establishes a link between two tables. It ensures referential integrity by enforcing the constraint that values in the foreign key column(s) must match values in the primary key column(s) of the referenced table.

13. What is a deadlock in DB2?

    A deadlock in DB2 occurs when two or more transactions are waiting for each other to release resources, resulting in a circular dependency. It can lead to a situation where none of the transactions can proceed.

14. What is the purpose of the COMMIT statement in DB2?

    The COMMIT statement in DB2 is used to permanently save the changes made in the current transaction. It ends the transaction and makes the changes visible to other users.

15. What is the purpose of the ROLLBACK statement in DB2?

    The ROLLBACK statement in DB2 is used to undo the changes made in the current transaction and restore the database to its previous state. It cancels the effects of the transaction.

16. What is the purpose of the LOCK TABLE statement in DB2?

    The LOCK TABLE statement in DB2 is used to lock one or more tables for exclusive access. It prevents other users from accessing or modifying the locked tables until the lock is released.

17. What is a join in DB2?

    A join in DB2 is a query operation that combines rows from two or more tables based on a related column between them. It allows you to retrieve data from multiple tables in a single query.

18. What is an index in DB2?

    An index in DB2 is a database object used to improve the performance of data retrieval operations. It allows the database engine to locate data more quickly using indexed values.

19. What is the purpose of the EXPLAIN statement in DB2?

    The EXPLAIN statement in DB2 is used to generate the execution plan for a SQL statement without actually executing it. It helps in analyzing and optimizing the performance of queries.

20. What is a check constraint in DB2?

    A check constraint in DB2 is a rule defined on a column or a set of columns to enforce data integrity. It specifies a condition that must be true for each row in the table.

21. What is a materialized view in DB2?

    A materialized view in DB2 is a database object that stores the result of a query in a precomputed form. It improves query performance by reducing the need to recompute the result each time the query is executed.

22. What is the purpose of the LOAD utility in DB2?

    The LOAD utility in DB2 is used to efficiently load large amounts of data into a table from an external source, such as a flat file. It is faster than using INSERT statements.

23. What is a data warehouse in DB2?

    A data warehouse in DB2 is a separate database that is optimized for reporting and analysis. It contains historical and aggregated data from various sources for decision-making purposes.

24. What is a DB2 catalog?

    A DB2 catalog is a set of system tables that contain metadata about the database, such as table definitions, column definitions, indexes, and access privileges.

25. What is a DB2 plan?

    A DB2 plan is an executable form of a DB2 program that contains the access plan and execution logic. It is stored in the database and can be executed by the DB2 engine.

26. What is a DB2 package?

    A DB2 package is a compiled version of a DB2 program that contains executable code. It is stored in the database and can be executed by the DB2 engine.

27. What is the purpose of the LOCK TABLE statement in DB2?

    The LOCK TABLE statement in DB2 is used to lock one or more tables for exclusive access. It prevents other users from accessing or modifying the locked tables until the lock is released.

28. What is a cursor in DB2?

    A cursor in DB2 is a database object used to retrieve and manipulate data row by row. It allows you to process query results one row at a time.

29. What is a stored procedure in DB2?

    A stored procedure in DB2 is a set of SQL and procedural statements that are stored and executed on the database server. It encapsulates business logic and can be called by applications.

30. What is a trigger in DB2?

    A trigger in DB2 is a database object that is automatically executed in response to a specific event, such as an INSERT, UPDATE, or DELETE operation on a table.

31. What is the difference between a primary key and a unique constraint in DB2?

    In DB2, a primary key is a set of one or more columns that uniquely identifies a row in a table. It enforces the constraint of uniqueness and does not allow NULL values. On the other hand, a unique constraint also enforces the constraint of uniqueness but allows NULL values.

32. What is a foreign key in DB2?

    A foreign key in DB2 is a column or a set of columns that establishes a link between two tables. It ensures referential integrity by enforcing the constraint that values in the foreign key column(s) must match values in the primary key column(s) of the referenced table.

33. What is a deadlock in DB2?

    A deadlock in DB2 occurs when two or more transactions are waiting for each other to release resources, resulting in a circular dependency. It can lead to a situation where none of the transactions can proceed.

34. What is the purpose of the COMMIT statement in DB2?

    The COMMIT statement in DB2 is used to permanently save the changes made in the current transaction. It ends the transaction and makes the changes visible to other users.

35. What is the purpose of the ROLLBACK statement in DB2?

    The ROLLBACK statement in DB2 is used to undo the changes made in the current transaction and restore the database to its previous state. It cancels the effects of the transaction.

36. What is the purpose of the LOCK TABLE statement in DB2?

    The LOCK TABLE statement in DB2 is used to lock one or more tables for exclusive access. It prevents other users from accessing or modifying the locked tables until the lock is released.

37. What is a join in DB2?

    A join in DB2 is a query operation that combines rows from two or more tables based on a related column between them. It allows you to retrieve data from multiple tables in a single query.

38. What is an index in DB2?

    An index in DB2 is a database object used to improve the performance of data retrieval operations. It allows the database engine to locate data more quickly using indexed values.

39. What is the purpose of the EXPLAIN statement in DB2?

    The EXPLAIN statement in DB2 is used to generate the execution plan for a SQL statement without actually executing it. It helps in analyzing and optimizing the performance of queries.

40. What is a check constraint in DB2?

    A check constraint in DB2 is a rule defined on a column or a set of columns to enforce data integrity. It specifies a condition that must be true for each row in the table.

41. What is a materialized view in DB2?

    A materialized view in DB2 is a database object that stores the result of a query in a precomputed form. It improves query performance by reducing the need to recompute the result each time the query is executed.

42. What is the purpose of the LOAD utility in DB2?

    The LOAD utility in DB2 is used to efficiently load large amounts of data into a table from an external source, such as a flat file. It is faster than using INSERT statements.

43. What is a data warehouse in DB2?

    A data warehouse in DB2 is a separate database that is optimized for reporting and analysis. It contains historical and aggregated data from various sources for decision-making purposes.

44. What is a DB2 catalog?

    A DB2 catalog is a set of system tables that contain metadata about the database, such as table definitions, column definitions, indexes, and access privileges.

45. What is a DB2 plan?

    A DB2 plan is an executable form of a DB2 program that contains the access plan and execution logic. It is stored in the database and can be executed by the DB2 engine.

46. What is the purpose of the BIND package statement in DB2?

    The BIND package statement in DB2 is used to bind a package to a plan. It associates the executable code of the package with the execution environment of the plan.

47. What is the purpose of the UPDATE statement in DB2?

    The UPDATE statement in DB2 is used to modify the values of one or more columns in one or more rows of a table. It allows you to change existing data in the database.

48. What is the purpose of the DELETE statement in DB2?

    The DELETE statement in DB2 is used to remove one or more rows from a table. It allows you to delete specific data from the database.

49. What is the purpose of the TRUNCATE TABLE statement in DB2?

    The TRUNCATE TABLE statement in DB2 is used to remove all rows from a table. It is faster than using DELETE statement as it deallocates the space used by the table.

50. What is a sequence in DB2?

    A sequence in DB2 is a database object used to generate unique numeric values automatically. It is often used to generate primary key values.

51. What is the purpose of the EXPORT utility in DB2?

    The EXPORT utility in DB2 is used to extract data from a table or a set of tables and store it in an external file. It allows you to create a backup of the data or transfer it to another system.

52. What is a user-defined function in DB2?

    A user-defined function in DB2 is a database object that encapsulates a set of SQL and procedural statements and can be called from SQL statements. It allows you to extend the functionality of DB2.

53. What is the purpose of the MERGE statement in DB2?

    The MERGE statement in DB2 is used to perform both INSERT and UPDATE operations on a target table based on a condition. It allows you to synchronize data between tables.

54. What is a global temporary table in DB2?

    A global temporary table in DB2 is a table that is created and used within a session. It is visible to all users and is automatically dropped at the end of the session.

55. What is the purpose of the REORG utility in DB2?

    The REORG utility in DB2 is used to reorganize the physical storage of a table or an index. It improves performance by optimizing disk space usage and reducing fragmentation.

56. What is a correlated subquery in DB2?

    A correlated subquery in DB2 is a subquery that refers to a column from the outer query. It allows you to perform operations based on values from the outer query.

57. What is the purpose of the RUNSTATS utility in DB2?

    The RUNSTATS utility in DB2 is used to collect statistics about the data in tables and indexes. It helps the query optimizer choose the most efficient access plan for queries.

58. What is a data type in DB2?

    A data type in DB2 defines the type of data that can be stored in a column or a variable. It determines the range of values and the operations that can be performed on the data.

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