Question

Using a distinct query with a case-insensitive collation like SQL_Latin1_General_CP1_CI_AS will retrieve the first occurrence of any case-insensitive rows.

But I want to retrieve the lower case if both cases are present.

If only one case is present in the data I want to retrieve that case. (unique occurrences of capital case should remain in capital case in the result set)

Table:

id | col1  
----------
1 | Ab  
2 | ab  
3 | cd  
4 | Cd  
5 | Ef 

Query:

SELECT DISTINCT [col1] COLLATE SQL_Latin1_General_CP1_CI_AS 
FROM dbo.table

Will retrieve: Ab, cd, Ef

But I want to retrieve: ab, cd, Ef

Are there collation that can give me my desired results?

Give priority to lower case instead of first case.

If not I have to use subselects.

1. Select all distinct values using case-sensitive collation (strangely is automatically sorted, almost the use case I wanted!)
2. Select from 1 using case-insensitive collation

Answer 1

May be something like this

select
    min(T.col1 collate SQL_Latin1_General_CP1_CS_AS)
from dbo.Table as T
group by T.col1 collate SQL_Latin1_General_CP1_CI_AS