[英]How to group by two columns?
請在下面考慮。 我想列出每個用戶預訂會議室的次數,以及他/她使用了多少個不同的房間:
room user
----------
1 1
2 1
3 2
4 3
4 3
所需的輸出:
user reservations rooms
-------------------------
1 2 2
2 1 1
3 2 1
誰能告訴我該怎么做?
我現在有:
select [user], count(1)
from [table]
group by [user]
但這並沒有給我房間數量。 添加另一個count()
不起作用。
您需要為房間count ( distinct <column> )
select [user], count(*) as reservations, count(distinct room) as rooms
from [table]
group by [user]
對房間使用聚合
Select user, count(*) reservation_ numbr,count(distinct room) as rooms
from t group by user
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