python_MySQL之间的增删改查
2017-08-06 20:36
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代码片段一
连接并执行sql
#encoding:UTF-8 import MySQLdb conn = MySQLdb.Connect( host = '127.0.0.1', port = 3306, user = 'root', passwd='123456', db='imooc', charset='utf8' ) cursor = conn.cursor() print conn print cursor sql = "select * from user" cursor.execute(sql) #执行
取数据
print cursor.rowcount #取数据 #fetchone()获取一条数据 #fetchany(3)获取多条 #fetchall()#获取客户缓冲区的所有数据 # rs = cursor.fetchone() # print rs # # rs = cursor.fetchmany(2) # print rs # # rs = cursor.fetchall() # print rs # rs = cursor.fetchall() # for row in rs: # print "userid=%s,username=%s" % row
更新数据库
# sql_insert = "insert into user(userid,username) values(10,'name10')" # sql_update = "update user set username='name91' where userid=9" # sql_delete = "delete from user where userid<3" # cursor.execute(sql_insert) # cursor.execute(sql_update) # cursor.execute(sql_delete) # #执行完后提交 # conn.commit() # #发生异常时回滚 # try: # sql_insert = "insert into user(userid,username) values(10,'name10')" # sql_update = "update user set username='name91' where userid=9" # sql_delete = "delete from user where userid<3" # cursor.execute(sql_insert) # cursor.execute(sql_update) # cursor.execute(sql_delete) # conn.commit() # except Exception as e: # print e # conn.rollback() cursor.close() conn.close()
代码片段2 银行实例
#coding:UTF-8 import sys import MySQLdb class TransferMoney(object): def __init__(self,conn): self.conn = conn def tranfer(self,source_acctid,target_acctid,money): try: self.check_acct_available(source_acctid) self.check_acct_available(target_acctid) self.has_enough_money(source_acctid,money) self.reduce_money(source_acctid,money) self.add_money(target_acctid,money) self.conn.commit() except Exception as e: self.conn.rollback() raise e def check_acct_available(self, acctid): cursor = self.conn.cursor() try: sql = "select * from account where acctid=%s"%acctid cursor.execute(sql) rs = cursor.fetchall() if len(rs)!=1: raise Exception("账号%s不存在"%acctid) finally: cursor.close() def has_enough_money(self, acctid, money): cursor = self.conn.cursor() try: sql = "select * from account where acctid=%s and money>%s" % (acctid,money) cursor.execute(sql) print "has_enough_money:"+sql rs = cursor.fetchall() if len(rs) != 1: raise Exception("账号%s没有足够的钱" % acctid) finally: cursor.close() def reduce_money(self, acctid, money): cursor = self.conn.cursor() try: sql = "update account set money=money-%s where acctid=%s" % (money,acctid) cursor.execute(sql) print "reduce_money:"+sql if cursor.rowcount != 1: raise Exception("账号%s减款失败" % acctid) finally: cursor.close() def add_money(self, acctid, money): cursor = self.conn.cursor() try: sql = "update account set money=money+%s where acctid=%s" % (money, acctid) cursor.execute(sql) print "reduce_money:" + sql if cursor.rowcount != 1: raise Exception("账号%s加款失败" % acctid) finally: cursor.close() if __name__ == "__main__": source_acctid = sys.argv[1] target_acctid = sys.argv[2] money = sys.argv[3] conn = MySQLdb.Connect( host='127.0.0.1', port=3306, user='root', passwd='123456', db='imooc', charset='utf8' ) tr_money = TransferMoney(conn) try: tr_money.tranfer(source_acctid,target_acctid,money) except Exception as e: print "出现问题了" + str(e) finally: conn.close()
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