import pymysql #导入 pymysql 
 
#打开数据库连接 
db= pymysql.connect(host="localhost",user="root", 
 password="123456",db="test",port=3307) 
 
# 使用cursor()方法获取操作游标 
cur = db.cursor() 
 
#1.查询操作 
# 编写sql 查询语句 user 对应我的表名 
sql = "select * from user" 
try: 
 cur.execute(sql) #执行sql语句 
 
 results = cur.fetchall() #获取查询的所有记录 
 print("id","name","password") 
 #遍历结果 
 for row in results : 
  id = row[0] 
  name = row[1] 
  password = row[2] 
  print(id,name,password) 
except Exception as e: 
 raise e 
finally: 
 db.close() #关闭连接 

import pymysql 
#2.插入操作 
db= pymysql.connect(host="localhost",user="root", 
 password="123456",db="test",port=3307) 
 
# 使用cursor()方法获取操作游标 
cur = db.cursor() 
 
sql_insert ="""insert into user(id,username,password) values(4,'liu','1234')""" 
 
try: 
 cur.execute(sql_insert) 
 #提交 
 db.commit() 
except Exception as e: 
 #错误回滚 
 db.rollback() 
finally: 
 db.close() 

import pymysql 
#3.更新操作 
db= pymysql.connect(host="localhost",user="root", 
 password="123456",db="test",port=3307) 
 
# 使用cursor()方法获取操作游标 
cur = db.cursor() 
 
sql_update ="update user set username = '%s' where id = %d" 
 
try: 
 cur.execute(sql_update % ("xiongda",3)) #像sql语句传递参数 
 #提交 
 db.commit() 
except Exception as e: 
 #错误回滚 
 db.rollback() 
finally: 
 db.close() 

import pymysql 
#4.删除操作 
db= pymysql.connect(host="localhost",user="root", 
 password="123456",db="test",port=3307) 
 
# 使用cursor()方法获取操作游标 
cur = db.cursor() 
 
sql_delete ="delete from user where id = %d" 
 
try: 
 cur.execute(sql_delete % (3)) #像sql语句传递参数 
 #提交 
 db.commit() 
except Exception as e: 
 #错误回滚 
 db.rollback() 
finally: 
 db.close()