mysql stored procedure view

MySQL stored procedure is a predefined program that can be stored and run on the database server. MySQL stored procedure is a storable, reusable program used to perform stateless database operations. In MySQL, a stored procedure consists of a series of SQL statements that accept parameters and return values.

In MySQL, stored procedures can be classified as user-defined functions or stored procedures. A user-defined function is a stand-alone callable program that accepts one or more parameters and returns a value. Stored procedures can perform one or more related operations and can accept zero or more parameters.

The syntax of MySQL stored procedures is similar to that of other programming languages, including procedure declaration, variable assignment, conditional statements, loop statements and exception handling. Stored procedures also support advanced features such as output parameters, cursors, and nested procedures.

The following is the basic syntax of a MySQL stored procedure:

DELIMITER //
CREATE PROCEDURE procedure_name(param1 datatype, param2 datatype, ..., paramN datatype)
BEGIN
    -- 这里是 SQL 语句
END //
DELIMITER ;

In this example, the DELIMITER command sets the delimiter of the MySQL interpreter to a double slash (//) to allow storage Use semicolons in procedures. The CREATE PROCEDURE command declares the name and parameters of the stored procedure. The body of a stored procedure consists of the SQL statements between BEGIN and END. Finally, the DELIMITER command returns the delimiter to a semicolon.

In order to execute the stored procedure, we can use the CALL command:

CALL procedure_name(param1, param2, ..., paramN);

In this example, the CALL command executes the stored procedure and passes the parameters to it. If the stored procedure returns a result set or output parameters, you can use the SELECT or SET command to obtain them.

With this basic knowledge in mind, we start looking at MySQL stored procedures. Listed below are several commonly used commands related to MySQL stored procedures.

1. SHOW CREATE PROCEDURE Command

SHOW CREATE PROCEDURE command is used to display the source code of the specified stored procedure. For example, if you want to view the source code of a stored procedure named myproc, you can execute the following command:

SHOW CREATE PROCEDURE myproc;

This will return the source code of the stored procedure, including its name, parameters, body, and delimiters. If the stored procedure uses special options (such as SQL SECURITY), they are also displayed.

2. SHOW PROCEDURE STATUS Command

The SHOW PROCEDURE STATUS command is used to display the status of all stored procedures defined in the current database. This command returns a result set that contains information such as the name, creation time, modification time, and execution times of each stored procedure. For example, to view the status of all stored procedures in the current database, you can execute the following command:

SHOW PROCEDURE STATUS;

3. DROP PROCEDURE command

The DROP PROCEDURE command is used to delete an existing stored procedures. If you are sure you want to delete a stored procedure, you can use the following command:

DROP PROCEDURE myproc;

This will delete the stored procedure named myproc.

4. ALTER PROCEDURE command

The ALTER PROCEDURE command is used to modify an existing stored procedure. The syntax of this command is very similar to the CREATE PROCEDURE command. It only needs to specify the part to be modified after the stored procedure name. For example, to modify the main part of the stored procedure named myproc, you can execute the following command:

ALTER PROCEDURE myproc
BEGIN
    -- 修改后的 SQL 语句
END;

5. USAGE command

USAGE command is used to display the storage information on the current MySQL server. Process usage. This command returns a result set that contains information such as the name, data type, parameter mode, and whether NULL values ​​are allowed for each stored procedure. For example, to view the usage of all stored procedures on the current MySQL server, you can execute the following command:

SELECT * FROM INFORMATION_SCHEMA.ROUTINES WHERE ROUTINE_TYPE='PROCEDURE';

Summary

MySQL stored procedures are a powerful database program that can help us improve the database performance and security. When you need to perform some complex transactions or use a large number of SQL statements, you can use stored procedures to simplify the code and improve the throughput of the database. The above commands are commands that beginners must master when learning MySQL stored procedures. Through these commands, they can better manage and use stored procedures.

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