如何在SELECT中没有列的情况下排序BY

Question

I am using MS-SQL and I have a table like this:

Count  Code
1      A
2      C
3      A
4      B
5      C
6      B

I need to only to get Distinct Row of the Code Column but I need to keep the Order of the Column to create a Comma Delimited String like this:

    A, C, B

I have tried the following code to not get an SQL Error of Msg 145, Level 15 - ORDER BY items must appear in the select list if SELECT DISTINCT is specified.

SELECT @tlist = ISNULL(@tlist+', ','') + Code 
FROM (SELECT DISTINCT t.Code  
     FROM @Table t) 

but I get an output of A, B, C

Answer 1

So, you don't want distinct . You want group by :

select t.code
from @Table t
group by t.code
order by min(count)

You can order by columns not mentioned in the select clause.

To get the comma delimited list as a single variable, use this technique:

select stuff((select ', '+t.code
              from @Table t
              group by t.code
              order by min(count)
              for xml path ('')
             ), 1, 2, '')

Order by in a subquery is generally undefined. And, your method of concatenating the list together in order is not guaranteed to work.

Answer 2

order them in your subquery

SELECT DISTINCT t.Code  
FROM @Table t
ORDER BY t.Code