Commonly used database operation methods in Python web development

Python, as a scripting language, is widely used in web development, and databases are a key part of web applications. In Python, we can use a variety of databases to store data, such as MySQL, PostgreSQL, MongoDB, etc.

For web developers, they must master database operation methods so that they can better utilize the database to support application logic. The following will introduce you to commonly used database operation methods in Python web development.

1. Connect to the database

The database connection object used in Python is the database connection object. According to different database types, different database connection modules need to be introduced. For example, MySQL needs to introduce the pymysql module, PostgreSQL needs to introduce the psycopg2 module, and MongoDB needs to introduce the pymongo module.

The following is a sample code to connect to the MySQL database:

import pymysql

# 数据库连接信息，可以通过读取配置文件或者通过参数传入
config = {
    'host': 'localhost',
    'port': 3306,
    'user': 'root',
    'password': '123456',
    'database': 'testdb'
}

# 连接数据库
conn = pymysql.connect(**config)

2. Create a database table

Creating a database table in Python uses a cursor object, and you need to obtain the cursor object first . Use a cursor object to execute the CREATE TABLE statement to create a table.

Sample code:

# 获取游标对象
cursor = conn.cursor()

# 创建表
sql = """
CREATE TABLE users (
    id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(30) NOT NULL,
    age INT,
    gender CHAR(1),
    email VARCHAR(50)
)
"""
cursor.execute(sql)

# 提交修改
conn.commit()

3. Query data

Querying database data also uses cursor objects. You can use the SELECT statement to query all data that meets the conditions. The query result is a two-dimensional array, the first dimension is the number of record rows, and the second dimension is the number of data columns.

Sample code:

# 查询数据
sql = """
SELECT id, name, age, gender, email
FROM users
WHERE age > 20
"""

cursor.execute(sql)

# 获取查询结果
results = cursor.fetchall()

# 打印结果
for row in results:
    id = row[0]
    name = row[1]
    age = row[2]
    gender = row[3]
    email = row[4]
    print(f"id={id}, name={name}, age={age}, gender={gender}, email={email}")

4. Insert data

Inserting data in Python uses a cursor object, and you can use the INSERT statement to insert data. To insert multiple pieces of data, use the executemany() method.

Sample code:

# 插入单条数据
sql = """
INSERT INTO users(name, age, gender, email)
VALUES("Tom", 25, "M", "tom@example.com")
"""
cursor.execute(sql)

# 插入多条数据
data = [
    ("Bob", 20, "M", "bob@example.com"),
    ("Alice", 28, "F", "alice@example.com")
]
sql = """
INSERT INTO users(name, age, gender, email)
VALUES(%s, %s, %s, %s)
"""
cursor.executemany(sql, data)

# 提交修改
conn.commit()

5. Update data

Using cursor objects to update database data, you can use the UPDATE statement to update data that meets the conditions.

Sample code:

# 更新数据
sql = """
UPDATE users
SET age=30, email='new_email@example.com'
WHERE name="Tom"
"""
cursor.execute(sql)

# 提交修改
conn.commit()

6. Delete data

To delete database data, you use a cursor object, and you can use the DELETE statement to delete data that meets the conditions.

Sample code:

# 删除数据
sql = """
DELETE FROM users
WHERE age < 25
"""
cursor.execute(sql)

# 提交修改
conn.commit()

Summary

Through the above introduction, we have learned about the common database operation methods in Python web development, including connecting to the database, creating database tables, Query data, insert data, update data and delete data.

In actual development, we need to choose the appropriate database type according to the needs of the application, and use the corresponding database connection module to connect to the database. At the same time, for database operations, exception handling needs to be performed in the code to ensure the stable operation of the program.

The above is the detailed content of Commonly used database operation methods in Python web development. For more information, please follow other related articles on the PHP Chinese website!