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我目前的查询中有一个部分与此类似

, T3 AS (
          select 'FSA'            as tType, b.fsacd  as tBefore, c.fsacd  as tAfter from T1 as a , T2 as b,T2 as c where a.beforeID = b.tID and a.afterID =c.tID 
    union select 'Scale'          as tType, b.scd    as tBefore, c.scd    as tAfter from T1 as a , T2 as b,T2 as c where a.beforeID = b.tID and a.afterID =c.tID 
    union select 'Retail Source'  as tType, b.rsc    as tBefore, c.rsc    as tAfter from T1 as a , T2 as b,T2 as c where a.beforeID = b.tID and a.afterID =c.tID 
    union select 'Mix Match'      as tType, b.mmcd   as tBefore, c.mmcd   as tAfter from T1 as a , T2 as b,T2 as c where a.beforeID = b.tID and a.afterID =c.tID 
    union select 'Price Entry'    as tType, b.pecd   as tBefore, c.pecd   as tAfter from T1 as a , T2 as b,T2 as c where a.beforeID = b.tID and a.afterID =c.tID 
    union select 'Qntty Entry'    as tType, b.qecd   as tBefore, c.qecd   as tAfter from T1 as a , T2 as b,T2 as c where a.beforeID = b.tID and a.afterID =c.tID    
    union select 'Price 3 Decs'   as tType, b.p3d    as tBefore, c.p3d    as tAfter from T1 as a , T2 as b,T2 as c where a.beforeID = b.tID and a.afterID =c.tID    
    union select 'Tare Entry'     as tType, b.tecd   as tBefore, c.tecd   as tAfter from T1 as a , T2 as b,T2 as c where a.beforeID = b.tID and a.afterID =c.tID    
    union select 'Undiscountable' as tType, b.undsc  as tBefore, c.undsc  as tAfter from T1 as a , T2 as b,T2 as c where a.beforeID = b.tID and a.afterID =c.tID    
    union select 'Foodstamp'      as tType, b.fds    as tBefore, c.fds    as tAfter from T1 as a , T2 as b,T2 as c where a.beforeID = b.tID and a.afterID =c.tID    
    union select 'WIC'            as tType, b.wic    as tBefore, c.wic    as tAfter from T1 as a , T2 as b,T2 as c where a.beforeID = b.tID and a.afterID =c.tID    
)

它工作正常，但我想让它看起来更紧凑。有没有办法构造一个函数foo，这样我就可以通过做一些看起来像这样的事情来完成相同的结果

, T3 AS (
          foo('FSA'             ,fsacd  ,T1, T2 ) 
    union foo('Scale'           ,scd    ,T1, T2 ) 
    union foo('Retail Source'   ,rsc    ,T1, T2 ) 
    union foo('Mix Match'       ,mmcd   ,T1, T2 ) 
    union foo('Price Entry'     ,pecd   ,T1, T2 ) 
    union foo('Qntty Entry'     ,qecd   ,T1, T2 )   
    union foo('Price 3 Decs'    ,p3d    ,T1, T2 )   
    union foo('Tare Entry'      ,tecd   ,T1, T2 )   
    union foo('Undiscountable'  ,undsc  ,T1, T2 )   
    union foo('Foodstamp'       ,fds    ,T1, T2 )   
    union foo('WIC'             ,wic    ,T1, T2 )   
)
4

1 回答 1

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这是另一种选择，但不确定它是否使问题变得更糟。这增加了 with 子句中的别名数量。但是请注意，当使用 UNION 或 UNION ALL 时，您只需在第一个子查询中指定新的列名。

tbefore as (select *
            from T1 a join
                 T2 b
                 on a.beforeID = b.tID
             ),
 tafter as (select *
            from T1 a join
                 T2 c
                 on a.afterID = b.tID
             ),
 t3b as (select 'FSA' as tType, fsacd as tBefore from tbefore union all
         select 'Scale'as tType, scd from tbefore union all
         ...
        ),
 t3a as (select 'FSA' as tType, fsacd as tAfter from tafter union all
         select 'Scale'as tType, scd from tafter union all
         ...
        ),
 t3 as (select t3b.ttype, t3b.tbefore, t3a.tafter
        from t3b join t3a on t3b.ttype = t3a.ttype
       )
于 2012-07-17T17:50:45.540 回答