python入门23 pymssql模块（python连接sql server增删改数据 ）

增删改数据必须connect.commit()才会生效 

回滚函数 connect.rollback()

连接数据库

'''
dinghanhua
sql server增删改
'''

import pymssql

server = '192.168.1.1'
user = 'user'
password = '111111'
database = 'test'

dbconnect = pymssql.connect(server = server,user = user,password=password,database = database) #连接到数据库

修改数据

dbcursor.execute("update test_student set name =%s where sno =1",'peter pan')
dbcursor.execute("update test_student set name =%s where sno =2",'silina smith')
dbconnect.commit() #增删改数据后必须commit

删除数据

dbcursor.execute("delete from test_student  where sno =1",'peter pan')
dbconnect.commit() #增删改数据后必须commit

新增数据

dbcursor.execute("insert into test_teacher values(%d,%s,%s)",(2,'xingxing','111111'))
dbconnect.commit() #增删改数据后必须commit

commit多个

dbcursor.execute("insert into test_teacher values(%d,%s,%s)",(6,'xingxing6','111111'))
dbcursor.execute("update test_student set name =%s where sno =2",'peter Panpan')
dbconnect.commit() #提交多个

commit之前，游标再执行select取出的都是未提交的数据

rollback()

dbcursor.execute("insert into test_teacher values(%d,%s,%s)",(7,'xingxing7','111111'))
dbconnect.rollback() #回滚
dbcursor.execute("update test_student set name =%s where sno =2",'peter')
dbconnect.commit()  #提交

最后关闭连接

dbcursor.close()
dbconnect.close()

commit之后数据库数据已变更，回滚是无效的，必须commit之前回滚。commit之前可以做下判断。

#避免delete或update未加where语句
with  pymssql.connect(server = server,user = user,password=password,database = database)  as dbconnect:
    with dbconnect.cursor() as dbcursor:
        dbcursor.execute("delete from test_teacher")  #假设忘记加delete

        dbcursor.execute("select count(1) from test_teacher") #查询下删除后数据个数
        if dbcursor.fetchone()[0] == 0:
            dbconnect.rollback() #回滚
        else:
            dbconnect.commit()

 

with as  替代手工关闭

with  pymssql.connect(server = server,user = user,password=password,database = database)  as dbconnect:
    with dbconnect.cursor(as_dict=True) as dbcursor:

        dbcursor.execute("insert into test_teacher values(%d,%s,%s)",(7,'xingxing7','111111'))
        dbconnect.rollback() #回滚
        dbcursor.execute("update test_student set name =%s where sno =2",'peter234')

        dbcursor.execute("select * from test_student")
        print(dbcursor.fetchall()) #取出的是未提交的数据

        dbconnect.commit()

the end！