mysql 找重复数据

SELECT email, COUNT(*)
FROM users
GROUP BY email
HAVING COUNT(*) > 1;

DELETE t1 FROM users t1
INNER JOIN users t2 
WHERE t1.id < t2.id AND t1.email = t2.email;

SELECT email, GROUP_CONCAT(address SEPARATOR '; ') as addresses
FROM users
GROUP BY email;

ALTER TABLE users ADD UNIQUE (email);

# 示例代码（Python）
import mysql.connector

db = mysql.connector.connect(host="localhost", user="user", password="password", database="database")
cursor = db.cursor()

email = "example@example.com"
check_query = "SELECT * FROM users WHERE email = %s"
cursor.execute(check_query, (email,))
result = cursor.fetchone()

if not result:
    insert_query = "INSERT INTO users (email) VALUES (%s)"
    cursor.execute(insert_query, (email,))
    db.commit()