使用筛选器来选取

从表中选择记录时，可以使用 "WHERE" 语句对选择进行筛选：

示例代码：

选择记录为 "Park Lane 38" 的记录，结果：

import mysql.connector
mydb = mysql.connector.connect(
  host="localhost",
  user="yourusername",
  passwd="yourpassword",
  database="mydatabase"
)
mycursor = mydb.cursor()
sql = "SELECT * FROM customers WHERE address ='Park Lane 38'"
mycursor.execute(sql)
myresult = mycursor.fetchall()
for x in myresult:
  print(x)

完整实例：

import mysql.connector
mydb = mysql.connector.connect(
  host="localhost",
  user="myusername",
  passwd="mypassword",
  database="mydatabase"
)
mycursor = mydb.cursor()
sql = "SELECT * FROM customers WHERE address = 'Park Lane 38'"
mycursor.execute(sql)
myresult = mycursor.fetchall()
for x in myresult:
  print(x)

通配符

您也可以选择以给定字母或短语开头、包含或结束的记录。

请使用 ％ 表示通配符：

示例代码：

选择地址中包含单词 "way" 的记录：

import mysql.connector
mydb = mysql.connector.connect(
  host="localhost",
  user="yourusername",
  passwd="yourpassword",
  database="mydatabase"
)
mycursor = mydb.cursor()
sql = "SELECT * FROM customers WHERE address LIKE '%way%'"
mycursor.execute(sql)
myresult = mycursor.fetchall()
for x in myresult:
  print(x)

完整实例：

import mysql.connector
mydb = mysql.connector.connect(
  host="localhost",
  user="myusername",
  passwd="mypassword",
  database="mydatabase"
)
mycursor = mydb.cursor()
sql = "SELECT * FROM customers WHERE address Like '%way%'"
mycursor.execute(sql)
myresult = mycursor.fetchall()
for x in myresult:
  print(x)

防止 SQL 注入

当用户提供查询值时，您应该转义这些值。

此举是为了防止 SQL 注入，这是一种常见的网络黑客技术，可以破坏或滥用您的数据库。

mysql.connector 模块拥有转义查询值的方法：

示例代码：

使用占位符 ％s 方法来转义查询值：

import mysql.connector
mydb = mysql.connector.connect(
  host="localhost",
  user="yourusername",
  passwd="yourpassword",
  database="mydatabase"
)
mycursor = mydb.cursor()
sql = "SELECT * FROM customers WHERE address = %s"
adr = ("Yellow Garden 2", )
mycursor.execute(sql, adr)
myresult = mycursor.fetchall()
for x in myresult:
  print(x)

完整实例：

import mysql.connector
mydb = mysql.connector.connect(
  host="localhost",
  user="myusername",
  passwd="mypassword",
  database="mydatabase"
)
mycursor = mydb.cursor()
sql = "SELECT * FROM customers WHERE address = %s"
adr = ("Yellow Garden 2", )
mycursor.execute(sql, adr)
myresult = mycursor.fetchall()
for x in myresult:
  print(x)