本文介绍了如何在按客户分组中放置计数器的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
它们是同一列
Name-Category
A-SL
B-SL
C-SL
A-SL
A-SL
C-SL
现在在我的脚本中，我将它们分组到类别中，但我想计算它们在查询中出现的次数.请看下面:
now in my script, i group them in Category but i want to count on how many times they occur in the query. please see below:
Customer-Line#
A-1 (means its the first time it occurs)
A-2 (means its the second time it occurs)
A-3 (means its the third time it occurs)
....so on
----------
B-1 (means its the first time it occurs)
----------
C-1 (means its the first time it occurs)
C-2 (means its the second time it occurs)
抱歉造成混乱，希望大家都清楚.
sorry for confusion, hope its clear for everyone.
谢谢，
推荐答案
您可以使用 row_number() 给同名的客户添加一个数字:
You can use row_number() to add a number to customers with the same name:
select name + '-' + cast(row_number() over (
partition by name order by id) as varchar(24))
from YourTable
如果只有在有多个客户时才需要号码，您可以使用 case when ... then ... end 表达式:
If the number is only required if there is more than one customer, you can use a case when ... then ... end expression:
select name +
case
when count(*) over (partition by name) = 1 then ''
else '-' + cast(row_number() over (
partition by name order by id) as varchar(24))
end
from YourTable
SQL Fiddle 示例.
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