Declare Variables in DB2

In IBM DB2, you can declare variables within a compound SQL (SQL PL) block or within a stored procedure. Here's how you can declare variables in DB2:

1. Declare Variables in Compound SQL Blocks:

   To declare variables within a compound SQL block, you can use the `DECLARE` keyword followed by the variable name and its data type. Optionally, you can specify an initial value for the variable.

   Example:

  

   BEGIN

       DECLARE var_name VARCHAR(50);

       DECLARE var_age INT DEFAULT 30;

       DECLARE var_balance DECIMAL(10,2);

       

       -- Your SQL PL code here

   END

   

   In this example, we declared three variables `var_name`, `var_age`, and `var_balance` of types VARCHAR, INT, and DECIMAL respectively within a compound SQL block.

2. Declare Variables in Stored Procedures:

   Variables can also be declared within stored procedures using the `DECLARE` statement.

   Example:

  

   CREATE PROCEDURE example_procedure()

   BEGIN

       DECLARE var_name VARCHAR(50);

       DECLARE var_age INT DEFAULT 30;

       DECLARE var_balance DECIMAL(10,2);

       

       -- Your stored procedure code here

   END

   

   In this example, we declared three variables `var_name`, `var_age`, and `var_balance` of types VARCHAR, INT, and DECIMAL respectively within a stored procedure.

Variables in DB2 provide flexibility and are widely used in stored procedures and compound SQL blocks for data manipulation operations within the DB2 environment.

Here are five frequently asked questions (FAQs) about declaring variables in IBM DB2:

1. Can I declare variables within SQL queries in DB2?

   - Answer: No, in IBM DB2, you cannot declare variables directly within SQL queries. Variables can only be declared within a compound SQL block or a stored procedure.

2. What types of variables can I declare in DB2 compound SQL blocks and stored procedures?

   - Answer: In IBM DB2, you can declare various types of variables, including scalar variables (e.g., VARCHAR, INT), date and time types (e.g., DATE, TIMESTAMP), and complex types (e.g., XML, JSON).

3. Can I use session variables in DB2 to store temporary data?

   - Answer: Yes, DB2 supports session variables, which can be used to store temporary data within a session. Session variables are prefixed with the `@` symbol.

4. What is the scope of variables declared in DB2 compound SQL blocks and stored procedures?

   - Answer: The scope of variables declared in DB2 compound SQL blocks and stored procedures is limited to the block or procedure in which they are declared. Variables declared in nested blocks have a narrower scope and can only be accessed within the block in which they are declared.

5. Can I assign a default value to a variable when declaring it in DB2?

   - Answer: Yes, you can assign a default value to a variable when declaring it in DB2 compound SQL blocks and stored procedures. This default value will be used if no other value is explicitly assigned to the variable during runtime.