How to read database data in mysql

MySQL reads database data

MySQL provides a variety of methods to read data in the database. This article will focus on the two most commonly used methods:

SELECT statement

The SELECT statement is the most commonly used method for reading from a database. It is used to extract data from one or more tables. The general syntax of a SELECT statement is as follows:

<code>SELECT <列名>
FROM <表名>
[WHERE <条件>]
[GROUP BY <列名>]
[HAVING <条件>]
[ORDER BY <列名>]
[LIMIT <行数>]</code>

Example:

Select all customers' names and emails from the customers table:

<code class="sql">SELECT name, email
FROM customers;</code>

fetchall() method

fetchall() method is another way to read data when interacting with MySQL using Python. fetchall() The method stores all result rows in a list of tuples, each tuple representing a row of data.

Example:

Use Python's mysql.connector library to read the names and values ​​of all customers from the customers table Email:

<code class="python">import mysql.connector

# 建立数据库连接
connection = mysql.connector.connect(
    host='localhost',
    user='root',
    password='',
    database='database_name'
)

# 创建游标对象
cursor = connection.cursor()

# 执行查询
cursor.execute("SELECT name, email FROM customers")

# 存储结果
result = cursor.fetchall()

# 遍历结果
for name, email in result:
    print(f'{name} - {email}')

# 关闭游标和连接
cursor.close()
connection.close()</code>

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