Create Table TEST(客户 Nvarchar(100))
Insert TEST Select N'A厂'
Union All Select N'A厂'
Union All Select N'A厂'
Union All Select N'B厂'
Union All Select N'B厂'
GO
Select ID=Identity(Int,1,1),* Into #T From TEST
Select 客户,(Select Count(*) From #T Where 客户=A.客户 And ID<=A.ID) As 出现次数 From #T A
Drop Table #T
GO
Drop Table TEST
--Result
/*
客户 出现次数
A厂 1
A厂 2
A厂 3
B厂 1
B厂 2
*/