c# - SQL 计数不符合我想要的结果

Question

我有两个不同的表 Products 和 ProductImages:

SELECT COUNT(p.productid) AS product_count, COUNT(pi.imageid) AS image_count  
FROM [Products] p, [ProductImages] pi  
WHERE p.productid=126 AND pi.productid=126;  

以上查询为我提供了每个 COUNT 中两个计数的乘积。请指导我哪里错了，我可以用单选查询来做吗。

Answer 1

你可以把它分成两行

SELECT COUNT(p.productid) As Count
FROM [Products] p
WHERE p.productid=126
UNION All
SELECT COUNT(pi.imageid) As Count
FROM  [ProductImages] pi 
WHERE pi.productid=126;

或者您可以在没有 UNION ALL

的情况下执行此操作

SELECT 
(SELECT COUNT(p.productid) As Count 
From [Products] p WHERE p.productid=126) ) as t1,
(SELECT COUNT(pi.imageid) As Count 
FROM  [ProductImages] pi WHERE pi.productid=126) as t2