select select（*）from

Question

我想從以下查詢中獲取行計數。我只有行數爲1，但有35個記錄。你能否讓我知道如何從內部查詢中獲得計數？

謝謝

SELECT COUNT(*)(SELECT DISTINCT a.my_id, a.last_name, a.first_name, b.temp_val 
       FROM Table_A a INNER JOIN Table_B b on a.a_id = b.a_id) 

Answer 1

你缺少FROM，你需要給子查詢的別名。

SELECT COUNT(*) FROM 
(
    SELECT DISTINCT a.my_id, a.last_name, a.first_name, b.temp_val 
    FROM dbo.Table_A AS a 
    INNER JOIN dbo.Table_B AS b 
    ON a.a_id = b.a_id 
) AS subquery;