python操作mysql数据库练习
本次练习是在windows下，mysql版本为5.7，python版本为2.7.5,集成环境为pycharm。
创建表时，enign在innodb下支持事务，其他可能不支持。
create table account( accid int(11) default null , money int(11) default null )engine=innodb;
一、测试环境
1 #coding=utf-8 2 import MySQLdb 3 4 conn=MySQLdb.connect(host='127.0.0.1',port=3306,user='root',passwd='771994001o',db='immc',charset='utf8') 5 cursor=conn.cursor() 6 7 print conn 8 print cursor 9 10 cursor.close()11 conn.close()
二、相关函数
#支持execute()执行一个数据库查询命令,执行sql,将结果从数据库放回到客户端 #fetchon()取结果集的下一行,移动rownumbr,返回数据 # fetchmany()取结果集的下几行 # fetchall()取结果集中的剩余所有行 # rowcount()最近一次execute返回数据的行数或影响行数 # close()关闭游标对象
三、使用select查询数据
1 conn=MySQLdb.connect(host='127.0.0.1',port=3306,user='root',passwd='771994001o',db='immc',charset='utf8') 2 cursor=conn.cursor() 3 4 sql="select * from manager" 5 cursor.execute(sql) 6 print cursor.rowcount 7 8 rs=cursor.fetchone() 9 print rs10 print rs[1]11 12 rs=cursor.fetchmany(3)13 print rs14 15 rs=cursor.fetchall()16 print rs17 18 cursor.close()19 conn.close()20 21 22 conn=MySQLdb.connect(host='127.0.0.1',port=3306,user='root',passwd='771994001o',db='immc',charset='utf8')23 cursor=conn.cursor()24 25 sql="select * from manager"26 cursor.execute(sql)27 28 rs=cursor.fetchall()29 for row in rs:30 print "UserId:%s,UserName:%s" %row31 32 cursor.close()33 conn.close()
四、更新数据库
1 conn=MySQLdb.connect(host='127.0.0.1',port=3306,user='root',passwd='771994001o',db='immc',charset='utf8') 2 cursor=conn.cursor() 3 4 sql_insert="insert into manager values(10010,'李隆基')" 5 sql_update="update manager set name='李开' where id=10023" 6 sql_delete="delete from manager where d<1003" 7 8 try: 9 cursor.execute(sql_insert)10 print cursor.rowcount11 cursor.execute(sql_update)12 print cursor.rowcount13 cursor.execute(sql_delete)14 print cursor.rowcount15 except Exception as e:16 print e17 conn.rollback()18 19 conn.commit()20 21 cursor.close()22 conn.close()
五、实例演练
开始事务-检测A和B账户是否可用-检测账户A是否有100块-账户A减去100快，账户B加上100块-提交事务
1 import sys 2 class TransfrMoney(object): 3 def __init__(self,conn): 4 self.conn=conn 5 def transfer(self,source_accid,target_accid,money): 6 try: 7 self.check_acct_available(source_accid) 8 self.check_acct_available(target_accid) 9 self.enough_moner(source_accid,money)10 self.reduce_money(source_accid,money)11 self.add_money(target_accid,money)12 self.conn.commit()13 except Exception as e:14 self.conn.rollback()15 raise e16 17 def check_acct_available(self,accid):18 cursor = self.conn.cursor()19 try:20 sql = "select * from account where accid=%s" % accid21 cursor.execute(sql)22 print "check_acct_available:"+sql23 rs = cursor.fetchall()24 if len(rs) != 1:25 raise Exception("账号%s不存在" % accid)26 finally:27 cursor.close()28 29 def enough_moner(self,accid, money):30 cursor = self.conn.cursor()31 try:32 sql = "select * from account where accid=%s and money >=%s" %(accid,money)33 cursor.execute(sql)34 print "enough_moner:" + sql35 rs = cursor.fetchall()36 if len(rs) != 1:37 raise Exception("账号%s没有足够的钱" % accid)38 finally:39 cursor.close()40 def reduce_money(self,accid,money):41 cursor = self.conn.cursor()42 try:43 sql = "update account set money =money-%s where accid=%s" % (money, accid)44 cursor.execute(sql)45 print "reduce_money:" + sql46 rs = cursor.fetchall()47 if cursor.rowcount != 1:48 raise Exception("账号%s减款失败" % accid)49 finally:50 cursor.close()51 def add_money(self,accid,money):52 cursor = self.conn.cursor()53 try:54 sql = "update account set money =money+%s where accid=%s" % (money, accid)55 cursor.execute(sql)56 print "add_money:" + sql57 rs = cursor.fetchall()58 if cursor.rowcount != 1:59 raise Exception("账号%s加款失败" % accid)60 finally:61 cursor.close()62 63 if __name__=="__main__":64 source_accid=sys.argv[1]65 target_accid=sys.argv[2]66 money=sys.argv[3]67 68 conn=MySQLdb.connect(host='127.0.0.1',port=3306,user='root',passwd='771994001o',db='immc',charset='utf8')69 tr_money=TransfrMoney(conn)70 try:71 tr_money.transfer(source_accid,target_accid,money)72 except Exception as e:73 print "出现问题"+str(e)74 finally:75 conn.close() 点击run——Edit Configuratopn...---Scrip parameters选项输入测试数据。
2017-03-13 16:58:35