如何查询某些结果的数据

Question

好的，这是我的数据集

Event_ID |  WorkerNumberID
3        |  Worker1
3        |  Worker2
3        |  Worker2
3        |  Worker3
5        |  Worker4
5        |  Worker5
3        |  Null
5        |  Null

我希望我的查询返回以下内容。即使eventID 3有2个'worker2'，我仍然只想将它计为1个非空项，因为它们是相同的。

Event_ID | WorkerNumberIDCount (a count of not null items)
 3       |  3
 5       |  2

思想？

Answer 1

试试这个

SELECT Event_ID,COUNT(DISTINCT WorkerNumberID) AS WorkerNumberIDCount 
FROM TableName
WHERE  WorkerNumberID IS NOT NULL
Group By Event_ID