比較從嵌套SELECT中的外部SELECT計數？

Question

我有這樣的SQL查詢，

select * from (select * from .......) as a 
where 1 = case when CountOfInnerSelect = 1 Then 1 ELSE ............ 

是否有可能，我可以得到內選擇的計數外內選擇？

Answer 1

你的，因爲它是應用就像一個過濾器在這裏WHERE Clause沒有太大的意義。 （即;類似於WHERE myCount = 1）

SELECT * FROM 
(SELECT c1,c2,c3,..,Cn,COUNT(*) AS myCount 
FROM YourTable 
GROUP BY c1,c2,c3,..,Cn 
) A 
WHERE 1 = CASE myCount WHEN 1 THEN 1 ELSE... END 

Answer 2

是：

select * from (select count(0) as cnt from .......) as a 
where 1 = case when a.cnt = 1 Then 1 ELSE ............