從子查詢

Question

選擇，所以我有以下導致錯誤（對於那些有興趣的：ORA-00904：「的Bleh」：無效的標識符）樣本查詢

select bleh from (
      SELECT MIN(mtb.id) KEEP (DENSE_RANK FIRST ORDER BY mtb.id) "bleh" 
       FROM mytable mtb 
      WHERE mtb.filtered_field_one = 0 
       and mtb.filtered_field_two = 0 
      GROUP BY mtb.foreighn_id, mtb.id 
); 

如果我把它變成（注一與*）取代bleh：

select * from (
      SELECT MIN(mtb.id) KEEP (DENSE_RANK FIRST ORDER BY mtb.id) "bleh" 
       FROM mytable mtb 
      WHERE mtb.filtered_field_one = 0 
       and mtb.filtered_field_two = 0 
      GROUP BY mtb.foreighn_id, mtb.id 
); 

我得到的結果完全按照我期望的那樣從1日查詢，它看起來像命名的Bleh以恰當的值1列。

那麼爲什麼我不能選擇該列的名稱（別名）？

Answer 1

當您用"雙引號將名稱命名爲列時，數據庫需要按原樣調用它，同時還使用雙引號！因此，嘗試這樣的：即使我說as is我認爲，@Stawros提供的評論是一個有價值的信息和平

select bleh from (
     SELECT MIN(mtb.id) KEEP (DENSE_RANK FIRST ORDER BY mtb.id) bleh 
      FROM mytable mtb 
     WHERE mtb.filtered_field_one = 0 
      and mtb.filtered_field_two = 0 
     GROUP BY mtb.foreighn_id, mtb.id 
); 

：

至於

select "bleh" from (
     SELECT MIN(mtb.id) KEEP (DENSE_RANK FIRST ORDER BY mtb.id) "bleh" 
      FROM mytable mtb 
     WHERE mtb.filtered_field_one = 0 
      and mtb.filtered_field_two = 0 
     GROUP BY mtb.foreighn_id, mtb.id 
); 

還是這樣列命名在Oracle：

bleh = BLEH = Bleh 
but 
"bleh" <> "BLEH" <> "Bleh"