python实现的MySQL增删改查操作实例小结

#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

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

# 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()

#coding:UTF-8
import sys
import MySQLdb
class TransferMoney( ):
  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()