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import pymysql
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import logging
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import datetime
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def ShowList(conn,CardNum):
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if(CardNum==""):
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return "借书证号不能为空"
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try:
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cursor=conn.cursor()
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sql="select * from card where cnum=%s"
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cursor.execute(sql,CardNum)
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result=cursor.fetchone()
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#要看输入的卡号是不是有效的
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if result is None:
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return "无效的借书证号"
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sql="select bnum,bname,btime,rtime,times from book natural join borrow where cnum=%s"
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cursor.execute(sql,CardNum)
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result=cursor.fetchall()
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return result
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except Exception as e:
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logging.exception(e)
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return e
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def Borrow(conn,CardNum,BookNum):
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if(CardNum=="" or BookNum==""):
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return "不能为空"
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try:
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cursor=conn.cursor()
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sql="select times,rtime from borrow where cnum=%s and bnum=%s"
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cursor.execute(sql,(CardNum,BookNum))
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times=cursor.fetchone()
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if times is None:
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pass
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elif times[0]==1:
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r_time=times[1]
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r_time=r_time+datetime.timedelta(days=30)
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r_time=r_time.strftime("%Y-%m-%d %H:%M:%S")
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sql="update borrow set times=0,rtime=%s where cnum=%s and bnum=%s"
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cursor.execute(sql,(r_time,CardNum,BookNum))
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conn.commit()
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return (1,r_time)
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elif times[0]==0:
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return "续借次数已达上限"
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#前面要判断是否是续借，允许续借一次
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#判断完不是续借之后，还要判断是否借书数量已经达到上限
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sql="select numbers from card where cnum=%s"
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cursor.execute(sql,CardNum)
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result=cursor.fetchone()
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if result[0]>=10:
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return "借书数量超出上限"
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else:
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numbers=result[0]+1
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#
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sql="select bname,collection from book where bnum=%s"
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cursor.execute(sql,BookNum)
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result=cursor.fetchone()
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#此处的判断逻辑其实不是很好。。。先判断了是否超出上限，再判断的书是否存在。可能会导致用户为了借一本不存在的书，先去还书，回来才发现根本没有这本书
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if result is None:
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return "借书失败，书号不存在"
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if result[1]!=0:
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#借书成功
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bname=result[0]
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collection=result[1]-1
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sql="update book set collection=%s where bnum=%s"
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cursor.execute(sql,(collection,BookNum))
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b_time= datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S")
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r_time=(datetime.datetime.now()+datetime.timedelta(days=30)).strftime("%Y-%m-%d %H:%M:%S")
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sql="insert into borrow values(%s,%s,%s,%s,1)"
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cursor.execute(sql,(CardNum,BookNum,b_time,r_time))
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sql="update card set numbers=%s where cnum=%s"
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cursor.execute(sql,(numbers,CardNum))
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conn.commit()
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return (0,r_time,bname)
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else:
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#借书失败，因为库存不足
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#关于如何返回最早的还书时间这一点明天再说
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#查到的方法中，最起码可以把两个表join然后比较
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#但是我比较想用聚合函数来做，因为简单（datatime类型的数据不知道能不能用聚合函数）答案是能！
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sql="select min(rtime) from borrow where bnum=%s"
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cursor.execute(sql,BookNum)
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result=cursor.fetchone()
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r_time=result[0]
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r_time=r_time.strftime('%Y-%m-%d %H:%M:%S')
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return (2,r_time)
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except Exception as e:
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logging.exception(e)
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conn.rollback()
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return e |
