Introduction to Stored Procedures and Functions
MySQL allows you to encapsulate reusable logic within stored procedures and functions. These database objects offer several benefits, including improved performance, reduced network traffic, and enhanced security. Often, developers need to list or inspect these routines to understand database structure, debug issues, or manage existing code. This tutorial explains how to view and retrieve information about stored procedures and functions directly from the MySQL command line.
Listing Stored Procedures
The primary command for listing stored procedures is SHOW PROCEDURE STATUS. When executed, this command displays a table containing details about each stored procedure in the MySQL server. The output includes columns like Name, Definer, Created, Modified, Routine_type, and Comment.
SHOW PROCEDURE STATUS;
This will show all stored procedures across all databases on the server.
Listing Stored Functions
Similarly, you can list stored functions using the SHOW FUNCTION STATUS command. The output format is identical to SHOW PROCEDURE STATUS, allowing you to easily identify and manage functions.
SHOW FUNCTION STATUS;
Viewing the Definition of a Routine
To view the complete SQL code that defines a specific stored procedure or function, use the SHOW CREATE PROCEDURE or SHOW CREATE FUNCTION command, respectively. Replace procedure_name or function_name with the actual name of the routine you want to inspect.
SHOW CREATE PROCEDURE my_procedure;
SHOW CREATE FUNCTION my_function;
This command will output the CREATE PROCEDURE or CREATE FUNCTION statement used to define the routine, allowing you to see the exact code it contains.
Filtering by Database
By default, SHOW PROCEDURE STATUS and SHOW FUNCTION STATUS display routines from all databases on the server. To limit the results to a specific database, use the WHERE Db = 'database_name' clause. Replace 'database_name' with the name of the database you want to inspect.
SHOW PROCEDURE STATUS WHERE Db = 'mydatabase';
SHOW FUNCTION STATUS WHERE Db = 'mydatabase';
Accessing Routine Information via the mysql.proc Table
MySQL stores information about stored procedures and functions in the mysql.proc table. You can query this table directly using SELECT statements to retrieve specific information.
To list all procedure names:
SELECT name FROM mysql.proc WHERE type = 'PROCEDURE';
To retrieve all information about all stored procedures and functions:
SELECT * FROM mysql.proc;
You can add WHERE clauses to filter the results based on various criteria, such as db (database name) and type (either ‘PROCEDURE’ or ‘FUNCTION’). This provides a flexible way to query and analyze routine metadata.
Using HELP SHOW
The HELP SHOW command provides information about the SHOW statement and its various options. This can be helpful for discovering additional commands and filtering options that you may not be aware of.
HELP SHOW;
This will display a comprehensive list of SHOW commands and their usage, allowing you to explore different ways to inspect database objects.