How to write custom stored procedures, triggers and functions in MySQL using Python

How to write custom stored procedures, triggers and functions in MySQL using Python

The database's stored procedures, triggers and functions are a powerful tool. It can help us implement some complex operations and logic in the database. In MySQL, we can use Python to write custom stored procedures, triggers and functions. This article explains how to use Python to accomplish these tasks in MySQL and provides specific code examples.

1. Custom stored procedures

A stored procedure is a collection of database operations that can be called by a name, and can pass parameters and return results. The following is an example of a stored procedure written in Python:

import mysql.connector

def create_procedure():
    conn = mysql.connector.connect(
      host="localhost",
      user="yourusername",
      password="yourpassword",
      database="yourdatabase"
    )
    
    cursor = conn.cursor()
    
    sql = """
    CREATE PROCEDURE GetProduct(IN pro_id INT)
    BEGIN
      SELECT * FROM product WHERE id = pro_id;
    END"""
    
    cursor.execute(sql)
    
    conn.commit()
    print("存储过程创建成功！")
    
    cursor.close()
    conn.close()

create_procedure()

The above code uses the MySQL Connector/Python library to connect to the database and uses the CREATE PROCEDURE statement to create a stored procedure named GetProduct, which stores The process accepts an integer parameter pro_id, then queries the data in the product table based on the id, and returns the result.

2. Custom triggers

A trigger is a special object in a database table that automatically performs a series of operations when a specific event occurs. Here is an example of a trigger written in Python:

import mysql.connector

def create_trigger():
    conn = mysql.connector.connect(
      host="localhost",
      user="yourusername",
      password="yourpassword",
      database="yourdatabase"
    )
    
    cursor = conn.cursor()
    
    sql = """
    CREATE TRIGGER update_product_count
    AFTER INSERT ON order_item
    FOR EACH ROW
    BEGIN
      UPDATE product SET count = count - NEW.quantity WHERE id = NEW.product_id;
    END"""
    
    cursor.execute(sql)
    
    conn.commit()
    print("触发器创建成功！")
    
    cursor.close()
    conn.close()

create_trigger()

The above code uses the MySQL Connector/Python library to connect to the database and uses the CREATE TRIGGER statement to create a trigger named update_product_count, which triggers The program is automatically executed after inserting a new record into the order_item table, and the inventory is automatically updated by updating the quantity of the corresponding product in the product table.

3. Custom function

The function is a piece of reusable code that receives a certain input, processes the input and returns an output. Here is an example of a function written in Python:

import mysql.connector

def create_function():
    conn = mysql.connector.connect(
      host="localhost",
      user="yourusername",
      password="yourpassword",
      database="yourdatabase"
    )
    
    cursor = conn.cursor()
    
    sql = """
    CREATE FUNCTION GetProductPrice(pro_id INT) RETURNS DECIMAL(10,2)
    BEGIN
      DECLARE price DECIMAL(10,2);
      SELECT price INTO price FROM product WHERE id = pro_id;
      RETURN price;
    END"""
    
    cursor.execute(sql)
    
    conn.commit()
    print("函数创建成功！")
    
    cursor.close()
    conn.close()

create_function()

The above code uses the MySQL Connector/Python library to connect to the database and uses the CREATE FUNCTION statement to create a function called GetProductPrice that accepts a Integer parameter pro_id, then query the price of the corresponding product in the product table based on the id, and return the price.

Summary:

By using Python to write custom stored procedures, triggers and functions, we can implement more flexible and complex operations and logic in the MySQL database. Using the Python programming language allows us to complete these tasks more quickly and efficiently. I hope this article will help you write custom stored procedures, triggers and functions in MySQL using Python.

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