Question

I have the following query. I am trying to only add the values, if the value is not null so the whole variable doesnt end up as a null. Obviously this query below is erroring out, but I do not want to use an ISNULL check on the test column because it puts a comma at the end of the variable text. How would I do this without having the comma at the end of the variable text. Sometimes there will be nulls in the test column, and sometimes there will not be.

DECLARE @Test TABLE
(
    test varchar(20)
)

INSERT INTO @Test
SELECT 'adfasdfasd'
UNION ALL
SELECT NULL


DECLARE @DocID varchar(max)

SELECT CASE WHEN test IS NOT NULL THEN @DocID = COALESCE(@DocID + ',' ,'')  + test END
FROM @Test

SELECT @DocID

Answer 1

Either of the following should work

SELECT @DocID = COALESCE(@DocID + ',', '') + test
FROM   @Test
WHERE  test IS NOT NULL 

or

SELECT @DocID = CASE
                  WHEN test IS NULL THEN @DocID /*No-op. */
                  ELSE COALESCE(@DocID + ',', '') + test
                END
FROM   @Test