FROM子句中的CASE

Question

是否可以在t-sql查詢中的FROM子句中使用CASE？ 例如：

SELECT * 
FROM CASE 
    WHEN column_ = 'firstColumn' 
     THEN table_ t, firstTable fT 
    ELSE table_ t, secondTable sT 

Answer 1

謝謝大家對您的輸入。我真的結束了類似於Quassnoi的建議：

SELECT * 
FROM table_ t, firstTable fT 

UNION 

SELECT * 
FROM table_ t, secondTable sT 

我不知道我在想什麼。我應該早點明白這一點。

Answer 2

SELECT * 
FROM mytable t 
CROSS APPLY 
     (
     SELECT * 
     FROM firstTable ft 
     WHERE t.column = 'firstColumn' 
       AND ft.id = t.joincolumn 
     UNION ALL 
     SELECT * 
     FROM secondTable st 
     WHERE (t.column <> 'firstColumn' OR t.column IS NULL) 
       AND st.id = t.joincolumn 
     ) q