请教个 sqlalchemy 的查询方式,想把参数传递到执行语句上。。。 - V2EX
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qazwsxkevin

请教个 sqlalchemy 的查询方式,想把参数传递到执行语句上。。。

  •  
  •   qazwsxkevin Sep 27, 2019 4211 views
    This topic created in 2418 days ago, the information mentioned may be changed or developed.

    请教个 sqlalchemy 的查询方式,想把参数传递到执行语句上。。。

    写了个函数去解决频发 query 操作:

    #从数据库中检查物品名字,如果有,返回物品 ID def queryItemNameStrGetItemID(tblName,ItemName,engine,conn): tbl = Table(tblName, metadata,autoload=True,autoload_with=engine)#映射了 tblName 表 s = select([tbl.c.ItemID]).where(tbl.c.ItemName) == ItemName) res = conn.execute(s) #fetchall 结果只能一次有效 selectreSult = res.fetchall() #selectreSult 是一个 list if len(selectreSult) == 0:#如果没有内容 return None else: return (selectreSult[0])[0] 

    在程序上实现:

    main: ResultDF = pd.DataFrame(************) engine = create_engine('mysql+pymysql://root:[email protected]:3306/test?charset=utf8') querycOnn= engine.connect() for i in ResultDF.itertuples():#对 A 列的物品进行历遍 tmpDFItemNameStr =i[ResultDF.columns.get_loc("A 列") + 1]#从 df 中获取 A 队物品名 tmpID = queryTeamNameStrgetTeamID('iteam_nick',tmpDFItemNameStr ,engine,queryconn)#找 ID if tmpID: todoSomethingFunc(tmpID) print(tmpID,':',tmpDFItemNameStr) queryconn.close() 

    问题是在函数里这句:

    s = select([tbl.c.ItemID]).where(tbl.c.ItemName) == ItemName) 

    我想用把函数的参数作为表的字段名传入到这一句,是否可以做到?应该如何写?
    select 这个语句的.c.后面的语句,似乎不可以 str 拼接方式完成...

    s = select([tbl.c.AnyID]).where(tbl.c.AnyName) == ItemName)

    如:

    def queryItemNameStrGetItemID(tblName,ItemName,AnyID,AnyName,engine,conn): 

    这样传入?

    9 replies    2019-09-27 17:00:09 +08:00
    jiezhi
        1
    jiezhi  
       Sep 27, 2019 via iPhone
    改成 tbl.c[AnyID]这样的呢
    Latin
        2
    Latin  
       Sep 27, 2019
    提供下我目前做多条件的封装思路
    查询条件列为字典
    filter_dict = {
    "a":tb.cv.ItemName
    }

    根据列取值
    filter_list = [filter_dict.get("a") if a else None ]
    term = [element for element in term if element is not None]
    传递参数
    s = select([tbl.c.ItemID]).where(*term) == ItemName)
    然后欧了
    好像有点词不达意....
    仅供参考
    qazwsxkevin
        3
    qazwsxkevin  
    OP
       Sep 27, 2019
    @jiezhi,改成[],在函数部分能编译通过,但是在调用函数部分,字段名不知道应该如何才是正确传入?
    以下方式均不能传入:
    tmpID = AnalyFunc.queryTeamNameStrgetTeamID('iteam_nick',ItemID,ItemName,tmpDFItemNameStr ,engine,queryconn)
    tmpID = AnalyFunc.queryTeamNameStrgetTeamID('iteam_nick','ItemID','ItemName',tmpDFItemNameStr ,engine,queryconn)
    tmpID = AnalyFunc.queryTeamNameStrgetTeamID('iteam_nick',[ItemID],[ItemName],tmpDFItemNameStr ,engine,queryconn)
    tmpID = AnalyFunc.queryTeamNameStrgetTeamID('iteam_nick',*ItemID,*ItemName,tmpDFItemNameStr ,engine,queryconn)

    @Latin,抱歉,真的看不懂,似乎也不适合我这种传入方式?
    lolizeppelin
        4
    lolizeppelin  
       Sep 27, 2019
    你这简直不是再用 orm
    和直接撸 sql 有啥区别啊 233
    qazwsxkevin
        5
    qazwsxkevin  
    OP
       Sep 27, 2019
    @lolizeppelin 嗯嗯,是的,因为现在表名,表结构,表的字段会经常变化,用 ORM 的方式要做 class 预定义字段的类型,这个不好搞,如果是直撸,代码会简单很多,目前不用 ORM,至少能完成功能先(改 ORM 等表稳定了再改也容易),所以你说得很对,2333 无法避免。。。
    先看看目前这个坑怎么绕? ^_^
    weyou
        6
    weyou  
       Sep 27, 2019 via Android
    @qazwsxkevin 表稳不稳定和用不用 orm 没啥直接关系吧
    qazwsxkevin
        7
    qazwsxkevin  
    OP
       Sep 27, 2019
    @weyou 用 ORM 的话,不是要做一个 class 类定义了表结构先吗?! 表的字段类型 float,int 不对读写会有问题,也许我对 ORM 理解还不够深入吧。。。。
    suzaku
        8
    suzaku  
       Sep 27, 2019
    粗略的看了一下,你是希望传入动态字段?

    field = getattr(tbl.c, AnyName)
    s = select([tbl.c.AnyID]).where(field) == ItemName)

    这样?
    suzaku
        9
    suzaku  
       Sep 27, 2019
    更正:
    s = select([tbl.c.AnyID]).where(field == ItemName)
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