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

2.2插入操作

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()

2.3更新操作

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()

2.4删除操作

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()