How to write stored procedures in MySQL using Python

Title: Examples and practical guide for using Python to write stored procedures in MySQL

Using stored procedures in MySQL can effectively encapsulate complex database operations and improve Database execution efficiency and security. This article will introduce how to use Python to write MySQL stored procedures and provide specific code examples for reference.

1. Environment preparation
   Before you start, you need to ensure that the following environment is ready:
2. Install the MySQL database and ensure that you can connect to the database through Python's MySQLdb module.
3. Install Python’s MySQLdb module for interacting with the MySQL database.
4. Use a text editor to open a new Python file for writing the code for the stored procedure.
5. Writing stored procedures
   A stored procedure is a set of predefined SQL statements, which are encapsulated into a stored procedure using the BEGIN and END keywords in MySQL. The following is a simple example stored procedure for inserting a new record into the table named "users":

DELIMITER //
CREATE PROCEDURE insert_user(IN username VARCHAR(20), IN age INT)
BEGIN
  INSERT INTO users (username, age) VALUES (username, age);
END //
DELIMITER ;

In the above code, we first use the DELIMITER keyword to separate the command delimiter Change to // because multiple SQL statements contained in the stored procedure must end with a semicolon (;). Then, use the CREATE PROCEDURE keyword to define a stored procedure named insert_user, which accepts two parameters: username and age. A specific SQL statement is written between the BEGIN and END keywords to insert a new record into the users table.

3. Calling stored procedures using Python
   In Python, we can use the MySQLdb module to execute stored procedures. Below is a sample code that demonstrates how to call the above insert_user stored procedure using Python:

import MySQLdb

def call_insert_user(username, age):
    db = MySQLdb.connect(host="localhost", user="root", passwd="password", db="testdb")
    cursor = db.cursor()
    
    try:
        cursor.callproc('insert_user', (username, age))
        db.commit()
        print("存储过程成功执行")
    except Exception as e:
        db.rollback()
        print("存储过程执行失败：" + str(e))
    
    db.close()

# 调用存储过程
call_insert_user("John", 25)

In the above code, we first connect to the MySQL database using the MySQLdb module. Then, use the cursor.callproc function to call the stored procedure. The function accepts two parameters: the name of the stored procedure and a tuple of parameters. Finally, use db.commit() to commit the transaction and close the database connection.

4. Notes
   When writing stored procedures in Python, there are some things to pay attention to:
5. You need to use the DELIMITER keyword to set the command separator to //, to Ensure that multiple SQL statements in the stored procedure can be executed correctly.
6. In a stored procedure, you can use the DECLARE keyword to define variables and the SET keyword to assign values ​​to variables.
7. In stored procedures, you can use flow control statements such as IF, WHILE and FOR to process complex logic.

Summary:
This article introduces how to use Python to write stored procedures in MySQL and provides an example of inserting records. By encapsulating complex database operations, using stored procedures can improve the execution efficiency and security of the database. I hope this article will be helpful to everyone when writing stored procedures using MySQL and Python.

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