sql - 从选择中选择计数(*)

Question

我正在尝试从以下查询中获取行数。我只得到行数为 1，但有 35 条记录。您能否告诉我如何从内部查询中获取计数？

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

您缺少 FROM，需要为子查询指定一个别名。

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;