pymysql五步骤：

①导入pymysql模块

②创建连接

③获取游标

④执行SQL语句

⑤关闭连接（关闭游标，关闭连接）

pymysql添加数据表数据：

#导入模块
import pymysql
#建立连接
conn=pymysql.connect(host='127.0.0.1',port=3306,user='root',password='root',database='db_itheima',charset='utf8')
#获取游标
cursor=conn.cursor()
#执行sql代码
try:
    sql="insert into tb_student values(null,'赵云',33,'天津省')"
    result=cursor.execute(sql)
    print('sql语句执行成功,受影响的行数：',result)
    conn.commit()
except Exception as e:
    conn.rollback()
#关闭游标，关闭连接
cursor.close()
conn.close()

pymysql修改数据表数据：

import pymysql
conn=pymysql.connect(host='127.0.0.1',port=3306,user='root',password='root',database='db_itheima',charset='utf8')
cursor=conn.cursor()
try:
    sql="update tb_student set name='李白' where id=1"
    r=cursor.execute(sql)
    print(r)
    conn.commit()
except Exception as e:
    conn.rollback()
cursor.close()
conn.close()

pymysql删除数据表数据：

import pymysql
conn=pymysql.connect(host='127.0.0.1',port=3306,user='root',password='root',database='db_itheima',charset='utf8')
cursor=conn.cursor()
try:
    sql='delete from tb_student where id=1'
    r=cursor.execute(sql)
    print(r)
    conn.commit()
except Exception as e:
    conn.rollback()
cursor.close()
conn.close()

pymysql查询数据表数据：

import pymysql
conn=pymysql.connect(host='127.0.0.1',port=3306,user='root',password='root',database='db_itheima',charset='utf8')
cursor=conn.cursor()
sql='select * from tb_student where id = 2'
cursor.execute(sql)
for i in cursor.fetchall():
    print(i)
cursor.close()
conn.close()