Question

I saw a lot of examples using COALESCE and others “methods” for this purpose .Here is one of them:

     @result nvarchar(1024)
     SELECT @result = COALESCE(@result + ',', '') + column_name
     FROM some_table

expected: [value,value,value]

result:[value , value , value]

Has anybody this problem or I must find my mistake in something else?

Answer 1

It sounds like you might have whitespace in the column_name values. You should use LTRIM() and RTRIM() around the column_name to remove any whitespace.:

declare @result nvarchar(1024)

SELECT @result = COALESCE(@result + ',', '') + ltrim(rtrim(col1))
FROM yourtable

select @result

see SQL Fiddle with Demo

Or you can use REPLACE() on the final result to remove whitespaces:

declare @result nvarchar(1024)

SELECT @result = COALESCE(@result + ',', '') + col1
FROM yourtable

select replace(@result, ' ', '')

see SQL Fiddle with Demo