Calling DB2 Stored Procedures with Parameters

Calling DB2 Stored Procedures with Parameters | Generated by AI

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Assumptions and Context

Your query appears to refer to calling a stored procedure (likely a typo for “store procedure”) in an IBM database system, such as IBM DB2 (on Linux/Unix/Windows, z/OS, or iSeries). Stored procedures are executable scripts stored in the database that can accept input parameters, perform operations, and return output or results. The exact syntax depends on the programming language and IBM environment (e.g., SQL, COBOL, RPG, or Java via JDBC). I’ll focus on the most common case: SQL-based CALL statements in DB2, as this is standard for relational databases.

If you’re using a different IBM platform (e.g., IBM i CL commands, MQ, or Watson Query), provide more details for tailored advice.

How to Pass Parameters in a DB2 Stored Procedure Call

Stored procedures in DB2 are called using the CALL statement in SQL. Parameters are passed in a comma-separated list within parentheses, matching the procedure’s definition (e.g., IN for input, OUT for output, INOUT for both).

Step-by-Step Guide

Define or Know the Procedure Signature: Ensure you know the procedure’s name and parameters. For example, a procedure might be defined as:
```
CREATE PROCEDURE update_employee (IN emp_id INT, IN new_salary DECIMAL(10,2), OUT status_msg VARCHAR(100))
```
- Here, emp_id is input (IN), new_salary is input, and status_msg is output (OUT).
Use the CALL Statement: In a SQL environment (e.g., DB2 Command Line Processor, or embedded in programs like Java), call the procedure like this:
```
CALL update_employee(12345, 75000.00, ?);
```
- The ? is a placeholder for OUT parameters. In programmatic calls, handle outputs with result sets or host variables.
- Inputs are passed as literals or variables; outputs are captured via placeholders or bound variables.
Handling Parameter Types:
- IN parameters: Pass values directly (e.g., numbers, strings in quotes).
- OUT/INOUT parameters: Use ? in the CALL, then bind them in your code to retrieve values after execution.
- Match the order and types exactly; mismatches cause errors (e.g., SQLCODE -440 for invalid parameters).

In Code Examples:

Via DB2 CLP (Command Line): Direct SQL execution.
```
CALL my_proc('input_value', ?);
```
Retrieve OUT params with FETCH FIRST FROM or in scripts.

Via JDBC (Java):

CallableStatement stmt = conn.prepareCall("{CALL update_employee(?, ?, ?)}");
stmt.setInt(1, 12345);          // IN param
stmt.setBigDecimal(2, new java.math.BigDecimal("75000.00")); // IN param
stmt.registerOutParameter(3, Types.VARCHAR); // OUT param
stmt.execute();
String status = stmt.getString(3); // Retrieve OUT

Via RPG on IBM i: Use CALLP with variable declarations matching parameter types.

D PROC_PARAM    S                   LIKE(PARAM_TYPE)
PROC_PARAM = 'value';
CALLP MY_PROC(PROC_PARAM);

Error Handling: Check SQLSTATE or SQLCODE post-call; e.g., ‘00000’ means success.

Key Tips and Evidence

Evidence from DB2 Documentation: Per IBM’s official DB2 SQL Reference (e.g., for LUW v11.5 or z/OS), the CALL statement is defined with optional parameter lists. For instance, the syntax is: CALL procedure-name [(parameter [, parameter] ...)]. This matches industry standards for relational databases and is supported across DB2 variants for consistency (see IBM Knowledge Center).
Variations: In IBM i (AS400), procedures might use CL (Command Language) calls like CALL PGM(MYPROC) PARM('value') for RPG programs. For mainframe COBOL, embed EXEC SQL CALL... with host variables.
Testing: Use db2 describe routine procedure_name to inspect parameters before calling.
Limitations: Large parameter sets may need arrays or result sets; complex types require specific handling.

If this doesn’t match your setup (e.g., if it’s IBM Watson or another tool), share more context like the platform or language for precise instructions.

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