Convert SQL Server result set into string

Question

I am getting the result in SQL Server as

SELECT StudentId FROM Student WHERE condition = xyz 

I am getting the output like

 StudentId 1236  7656  8990 ........ 

The output parameter of the stored procedure is @studentId string and I want the return statement as

1236, 7656, 8990. 

How can I convert the output in the single string?

I am returning single column [ie. StudentId]

Answer 1

Test this:

 DECLARE @result NVARCHAR(MAX)   SELECT @result = STUFF(                         (   SELECT ',' + CONVERT(NVARCHAR(20), StudentId)                              FROM Student                              WHERE condition = abc                              FOR xml path('')                         )                         , 1                         , 1                         , '') 

Answer 2

DECLARE @result varchar(1000)  SELECT @result = ISNULL(@result, '') + StudentId + ',' FROM Student WHERE condition = xyz  select substring(@result, 0, len(@result) - 1) --trim extra "," at end