select select（*）from

Question

我想从以下查询中获取行计数。我只有行数为1，但有35个记录。你能否让我知道如何从内部查询中获得计数？

谢谢

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，你需要给子查询的别名。

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;