找到一条记录，即id_hash相同的最后一条记录，并将这两条记录的时间差记录在列中

# 导入数据库驱动和相关库
import mysql.connector

# 连接数据库
cnx = mysql.connector.connect(user='your_username', password='your_password',
                              host='your_host', database='your_database')
cursor = cnx.cursor()

# 查询具有相同id_hash的最后一条记录
query = "SELECT * FROM your_table WHERE id_hash = %s ORDER BY timestamp DESC LIMIT 2"
cursor.execute(query, (id_hash,))
records = cursor.fetchall()

# 计算时间差并将其记录在列中
time_diff = records[0]['timestamp'] - records[1]['timestamp']
update_query = "UPDATE your_table SET time_diff = %s WHERE id_hash = %s"
cursor.execute(update_query, (time_diff, id_hash))

# 提交更改并关闭连接
cnx.commit()
cursor.close()
cnx.close()