Question

我是PL / SQL的新手，我正试图尽可能快地学习它。
我试图做一个简单的SELECT，但我遇到了这个错误。
虽然我知道这意味着什么，但我真的不知道如何解决问题...

这是我的代码部分：

SELECT
    NVL(UPPER(T.COL1),'N.D.') COL1,
    V.SECO,
    'N' CL_MED,
    V.DEST_USO,
  (CASE  
    WHEN V.COL2 IS NULL
        AND V.SECO IN ('B090','B100') THEN ''
    WHEN V.COL2 LIKE 'L-DEF%' 
        OR V.COL2 LIKE 'L-FUI%' 
        AND V.SECO IN ('B090','B100') THEN 'FUI/DEF'
    WHEN V.COL2 IS NULL 
        AND V.SECO = 'B080' 
        AND V.COL3 LIKE 'DEF%'
        OR V.COL3 LIKE 'FUI%' THEN 'FUI/DEF'  
    ELSE ''
    END 
    ) FLAG_DEF_FUI
  FROM TAB1 V
  JOIN TAB2 C ON (V.COL4    = C.COL4
                 AND V.COL5       = C.COL5
                 AND V.COL6 = C.COL6)
  JOIN TAB3 T ON (V.COL4  = T.COL4
                  AND V.COL5 = T.COL5
                  AND V.COL5A = T.COL5A
                  AND T.COL6 =V.COL6)
  WHERE V.COL4 = :COL4
  AND V.COL6 = :COL6
  AND V.COL5 NOT IN
    (SELECT gcm.PDR
    FROM TAB4 gcm
    WHERE gcm.COL6 = :COL6
    )
  GROUP BY (UPPER(T.COL1),V.SECO, V.DEST_USO, FLAG_DEF_FUI)

和FLAG_DEF_FUI是导致此错误的列.....任何帮助？！

编辑：我不是在问为什么我不能在GROUP BY中使用别名。我问这个问题的解决方法......

Answer 1

为了对你拥有的复杂函数进行分组，我总是进行子选择。因此，您的查询将变为：

  select child_query.stuff, child_query.flag_def_fui
    from 
   (   
    select
        'some-stuff' some_stuff,
      (case  
        when v.col2 is null
            and v.seco in ('b090','b100') then ''
        when v.col2 like 'l-def%' 
            or v.col2 like 'l-fui%' 
            and v.seco in ('b090','b100') then 'fui/def'
        when v.col2 is null 
            and v.seco = 'b080' 
            and v.col3 like 'def%'
            or v.col3 like 'fui%' then 'fui/def'  
        else ''
        end 
        ) flag_def_fui
      from tab1 v
      join tab2 c
      on (v.col4    = c.col4
      and v.col5       = c.col5
      and v.col6 = c.col6)
      join tab3 t
      on (v.col4            = t.col4
      and v.col5               = t.col5
      and v.col5a              = t.col5a
      and t.col6         =v.col6)
      where v.col4          = :col4
      and v.col6         = :col6
      and v.col5 not          in
        (select gcm.pdr
        from tab4 gcm
        where gcm.col6 = :col6
        )
     )  child_query 
      group by child_query.stuff, child_query.flag_def_fui;

Answer 2

其他答案为您提供了两个选项并且都是正确的。为了清楚明白，并且要专门回答您编辑过的问题，您有三个选项可以解决无法在SELECT column_alias FROM (<your query>) GROUP BY column_alias;中引用别名列的问题：

1）Answer 1: Wrap your query以便容易引用列别名，即

DISTINCT

2）Answer 2: Don't use GROUP BY如果您不使用汇总功能，请改用GROUP BY。

3）将构成列的复杂表达式复制到SELECT CASE WHEN col1 = 1 THEN 'one' WHEN col1 = 2 THEN 'two' ELSE '' END as col1_alias, SUM(col2) as col2_alias, col3 FROM table_name GROUP BY CASE WHEN col1 = 1 THEN 'one' WHEN col1 = 2 THEN 'two' ELSE '' END, col3;，即

target

Answer 3

根据您所显示的内容，您根本不需要分组条款，因为您没有聚合函数（min，max等）。选择列表中的每一列都在group-by子句中。

如果您使用该子句来禁止重复，那么使用distinct关键字会更简单：

SELECT DISTINCT
    NVL(UPPER(T.COL1),'N.D.') COL1,
    V.SECO,
    'N' CL_MED,
    V.DEST_USO,
  (CASE  
    WHEN V.COL2 IS NULL
        AND V.SECO IN ('B090','B100') THEN ''
    WHEN V.COL2 LIKE 'L-DEF%' 
        OR V.COL2 LIKE 'L-FUI%' 
        AND V.SECO IN ('B090','B100') THEN 'FUI/DEF'
    WHEN V.COL2 IS NULL 
        AND V.SECO = 'B080' 
        AND V.COL3 LIKE 'DEF%'
        OR V.COL3 LIKE 'FUI%' THEN 'FUI/DEF'  
    ELSE ''
    END 
    ) FLAG_DEF_FUI
  FROM TAB1 V
  JOIN TAB2 C
  ON (V.COL4    = C.COL4
  AND V.COL5       = C.COL5
  AND V.COL6 = C.COL6)
  JOIN TAB3 T
  ON (V.COL4            = T.COL4
  AND V.COL5               = T.COL5
  AND V.COL5A              = T.COL5A
  AND T.COL6         =V.COL6)
  WHERE V.COL4          = :COL4
  AND V.COL6         = :COL6
  AND V.COL5 NOT          IN
    (SELECT gcm.PDR
    FROM TAB4 gcm
    WHERE gcm.COL6 = :COL6
    )

（您可能还想查看not exists支票是否比您现在拥有的not in更有效。）

ORA-00904 - 无效的标识符

3 个答案: