MySQL Stored Procedure Programming

Calling Stored Programs from Stored Programs

Calling one stored program from another is perfectly simple. You do this with the CALL statement, just as you would from the MySQL command-line client.

Figure 2-15 shows a simple stored procedure that chooses between two stored procedures based on an input parameter. The output of the stored procedure (l_bonus_amount is populated from an OUT parameter) is passed to a third procedure.

Here is an explanation of the significant lines:

Line(s)	Explanation
11	Determine if the employee is a manager. If he is a manager, we call the calc_manager_bonus stored procedure; if he is not a manager, we call the calc_minion_bonus stored procedure.
12 and 14	With both stored procedures, pass in the employee_id and provide a variable—l_bonus_amount—to receive the output of the stored procedure.
16	Call the grant_bonus stored procedure that passes as arguments the employee_id and the bonus amount, as calculated by the stored procedure we called in line 12 or 14.

Figure 2-15. Example of calling one stored procedure from another