过滤器计数子句 - 一对多关系

Question

我目前有两个表，其中一个 versionLog 可以包含许多 ProductVersion。

以下 Sql 查询：

SELECT
versionlog.[Name],
(
    SELECT COUNT(*) 
    FROM dbo.ProductVersions productVersion 
    WHERE productVersion.VersionLogId = versionLog.Id  
) AS ProductVersions
FROM dbo.Versionlog versionLog

产生一个结果集类似于

Name | ProductVersions
Log1  | 12
Log2  |  6
Log3  |  0

等等..

如何将结果集限制为仅返回 ProductVersion Count = 0 的 Versionlogs？

根据谷歌，我需要使用Having子句？

Answer 1

使用HAVING ：

SELECT versionlog.[Name]
FROM dbo.Versionlog versionLog
LEFT JOIN dbo.ProductVersions productVersion 
  ON productVersion.VersionLogId = versionLog.Id  
GROUP BY versionlog.[Name]
HAVING COUNT(productVersion.VersionLogId) = 0;

---

并且没有分组：

SELECT versionlog.[Name]
FROM dbo.Versionlog versionLog
LEFT JOIN dbo.ProductVersions productVersion 
  ON productVersion.VersionLogId = versionLog.Id  
WHERE productVersion.VersionLogId IS NULL

Answer 2

另一种方式子查询

select * from 
(
SELECT
versionlog.[Name],
(
    SELECT COUNT(*) 
    FROM dbo.ProductVersions productVersion 
    WHERE productVersion.VersionLogId = versionLog.Id  
) AS ProductVersions
FROM dbo.Versionlog versionLog
) a where a.ProductVersions=0