Top IBM DB2 Interview Questions and Answers

Here are top IBM Db2 interview questions,

1. What is IBM DB2?

IBM DB2 is a family of data management products developed by IBM that provide relational database management system (RDBMS) solutions for various platforms, including mainframes, mid-range servers, and distributed systems.

 

2. How do you create a new database in IBM DB2?

To create a new database in DB2, you can use the following SQL command:

      ```sql

      CREATE DATABASE database_name;

      ```

 

3. How do you connect to an IBM DB2 database using the command-line client?

To connect to an IBM DB2 database using the command-line client, use the `db2` command with the following syntax:

      ```

      db2 connect to database_name user username using password

      ```

      Replace `database_name`, `username`, and `password` with appropriate values.

 

4. What is the command to create a new table in IBM DB2?

The SQL command to create a new table is as follows:

      ```sql

      CREATE TABLE table_name (

          column1 datatype constraints,

          column2 datatype constraints,

          ...

      );

      ```

 

5. How do you insert data into an IBM DB2 table?

To insert data into a table, use the `INSERT INTO` statement as follows:

      ```sql

      INSERT INTO table_name (column1, column2, ...)

      VALUES (value1, value2, ...);

      ```

 

6. How can you retrieve all records from an IBM DB2 table?

You can use the `SELECT` statement without specifying any conditions to retrieve all records:

      ```sql

      SELECT * FROM table_name;

      ```

 

7. What is the purpose of the `WHERE` clause in IBM DB2?

The `WHERE` clause is used to filter records in a `SELECT`, `UPDATE`, or `DELETE` statement based on specified conditions.

 

8. How do you update data in an IBM DB2 table?

To update data in a table, use the `UPDATE` statement as follows:

      ```sql

      UPDATE table_name

      SET column1 = value1, column2 = value2, ...

      WHERE condition;

      ```

 

9. How can you delete records from an IBM DB2 table?

To delete records from a table, use the `DELETE FROM` statement along with the `WHERE` clause to specify the condition for deletion:

      ```sql

      DELETE FROM table_name

      WHERE condition;

      ```

 

10. What is the purpose of the `ORDER BY` clause in IBM DB2?

The `ORDER BY` clause is used to sort the result set based on one or more columns in ascending or descending order.

 

11. How do you create an index in IBM DB2?

To create an index on a column for faster data retrieval, use the `CREATE INDEX` statement:

       ```sql

       CREATE INDEX index_name ON table_name (column_name);

       ```

 

12. What are the isolation levels supported by IBM DB2?

IBM DB2 supports various isolation levels, including `READ UNCOMMITTED`, `READ COMMITTED`, `REPEATABLE READ`, and `SERIALIZABLE`, allowing control over concurrent data access and locking.

 

13. How do you perform a backup and restore in IBM DB2?

To perform a backup, you can use the `db2 backup` command, and to restore the backup, use the `db2 restore` command.

 

14. What is the purpose of stored procedures and user-defined functions in IBM DB2?

Stored procedures and user-defined functions allow you to encapsulate SQL and procedural logic, providing modular and reusable code for complex operations.

 

15. How can you implement referential integrity in IBM DB2?

Referential integrity can be enforced in DB2 by defining foreign key constraints that link the primary key of one table to the corresponding foreign key in another table.

 

16. How do you handle NULL values in IBM DB2?

NULL values in DB2 represent missing or unknown data. To handle NULL values, you can use the `IS NULL` or `IS NOT NULL` conditions in SQL queries.

 

17. What are the different types of table spaces in IBM DB2?

IBM DB2 supports several types of table spaces, including regular (SEGMENTED and SIMPLE), large, and universal table spaces, each designed for specific use cases and performance considerations.

 

18. How can you perform data compression in IBM DB2?

IBM DB2 provides table compression capabilities that allow you to reduce storage space and improve query performance by compressing data at the table level.

 

19. What is the purpose of the `FETCH FIRST` clause in IBM DB2?

The `FETCH FIRST` clause is used to limit the number of rows returned by a `SELECT` query, similar to the `LIMIT` clause in other databases.

 

20. How do you drop a table in IBM DB2?

To drop a table and remove it from the database, use the `DROP TABLE` statement:

       ```sql

       DROP TABLE table_name;

       ```

Above are few top IBM Db2 interview questions. Remember to prepare and expand on these answers.

Good luck with your interview!  👍