sql - 将列添加到 group by 子句会打乱计数

Question

我需要计算一列中重复项的数量，这样可以工作：

SELECT CorrelationId, Count(CorrelationId) as total
FROM VoipDetailsView
WHERE ResponseCode = 200
GROUP BY CorrelationId

但是，当我尝试将其他列添加到结果中时

SELECT SessionIdTime, CorrelationId, Count(CorrelationId) as total
FROM VoipDetailsView
WHERE ResponseCode = 200
GROUP BY CorrelationId, SessionIdTime
ORDER BY SessionIdTime 

所有计数现在都是 0 或 1，即使（或可能是因为）现在正在显示重复值。我不介意重复，但我需要最后一列包含每个选定的重复 CorrelationIds 的总数。（例如，如果该值存在两次，则这两行的计数均为 2）

我需要什么样的查询才能做到这一点？

Answer 1

SessionIdTime在列上使用聚合函数怎么样min()

SELECT min(SessionIdTime), CorrelationId, Count(CorrelationId) as total
FROM VoipDetailsView
WHERE ResponseCode = 200
GROUP BY CorrelationId
ORDER BY min(SessionIdTime)

Answer 2

您需要将 CorrelationId 的聚合分离到一个单独的查询中，并将其与您的表连接以获取其他列，例如：

SELECT v.SessionIdTime, v.CorrelationId, total
From VoipDetailsView v inner join
(SELECT CorrelationId, Count(CorrelationId) as total
FROM VoipDetailsView
WHERE ResponseCode = 200
GROUP BY CorrelationId) agg
on v.CorrelationId = agg.CorrelationId

Answer 3

您的第二个查询为您提供了特定 SessionIdTime 中重复 CorrelationId 的数量，这是您想要的吗？SessionIdTime 是什么意思？

顺便说一句，你可以这样做：

SELECT CorrelationId, Count(*) as total
FROM VoipDetailsView
WHERE ResponseCode = 200
GROUP BY CorrelationId;

它更优化了一些