使用pymysql对mysql进行增删改差

import pymysql
db=pymysql.connect(host='localhost',user='root',passwd='xxxxxx',db='pymysql',port=3306)
def select_one():
    sql='select * from tb_user'
    cursor=db.cursor()
    cursor.execute(sql)
    data=cursor.fetchone()
    return data

def select_by_id(id):
    sql='select * from tb_user where id=%d'%id
    cursor=db.cursor()
    cursor.execute(sql)
    data=cursor.fetchone()
    return data
def select_all():
    sql = 'select * from tb_user'
    cursor = db.cursor()
    cursor.execute(sql)
    datas= cursor.fetchall()
    return datas

def delete_one(id):
    sql='delete from tb_user where id=%d'%id
    cursor=db.cursor()
    cursor.execute(sql)

def insert_one():
    sql='insert into tb_user(id,name,age) values(2,"wanchao",18)'
    cursor=db.cursor()
    cursor.execute(sql)

def update():
    sql='update tb_user set name="gaohan" where name="wanchao"'
    cursor=db.cursor()
    cursor.execute(sql)

if __name__=='__main__':
    print('查询一条语句:{}'.format(select_one()))
    print('按id查询一条语句:{}'.format(select_by_id(2)))
    print('查询多条语句：')
    [ print(data) for data in select_all()]
    print('删除：')
    delete_one(2)
    [print(data) for data in select_all()]
    print('添加')
    insert_one()
    [print(data) for data in select_all()]
    print('修改:')
    update()
    [print(data) for data in select_all()]