SQL 无重复计数
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Counting without duplicates
提问by Marc
I have a table such as the following
我有一张如下表
FK_OrgId , FK_UserId
3 , 74
1 , 74
1 , 74
3 , 4
4 , 5
1 , 5
I'm trying to count FK_OrgId but I have to eliminate duplicates. So, I want a result like
我正在尝试计算 FK_OrgId 但我必须消除重复项。所以，我想要一个结果
FK_OrgId, count
3 , 2
1 , 2
4 , 1
Any suggestions?
有什么建议？
回答by John Woo
The key here is to use DISTINCTinside COUNT()so it will only count unique values.
这里的关键是使用DISTINCTinsideCOUNT()所以它只会计算唯一值。
SELECT FK_OrgId, COUNT(DISTINCT FK_UserId)
FROM TableName
GROUP BY FK_OrgId
OUTPUT
输出
╔══════════╦════════════╗
║ FK_ORGID ║ TOTALCOUNT ║
╠══════════╬════════════╣
║ 1 ║ 2 ║
║ 3 ║ 2 ║
║ 4 ║ 1 ║
╚══════════╩════════════╝
回答by Stephane Rolland
you should use distinctkey word so as to avoid dupplicates
你应该使用distinct关键字以避免重复
select t.FK_OrgId, count(distinct t.FK_UserId)
from TableName as t
group by t.FK_OrgId
