DECLARE @Test table(
	col1	int)
INSERT INTO @Test 
SELECT 1 UNION ALL SELECT 
2 UNION ALL  SELECT 
3 UNION ALL SELECT 
4 UNION ALL SELECT 
5 UNION ALL SELECT 
6 UNION ALL SELECT 
7 UNION ALL SELECT 
1 UNION ALL SELECT 
4 UNION ALL SELECT 
5;


WITH CTE AS(
SELECT CAST( (SELECT CAST( col1 AS varchar(10))+ ','
               FROM @Test b 
				FOR XML PATH('')
				) AS VARCHAR(MAX)) concat_string
		)
SELECT LEFT( concat_string, LEN(concat_string) - 1)
FROM CTE

DECLARE @Test table(
	col1	int)
INSERT INTO @Test 
SELECT 1 UNION ALL SELECT 
2 UNION ALL  SELECT 
3 UNION ALL SELECT 
4 UNION ALL SELECT 
5 UNION ALL SELECT 
6 UNION ALL SELECT 
7 UNION ALL SELECT 
1 UNION ALL SELECT 
4 UNION ALL SELECT 
5;


DECLARE @S VARCHAR(8000);

SELECT 
  @S = COALESCE(@S, '') + CAST(col1 AS VARCHAR(10)) + ',' 
FROM @Test;

SELECT LEFT(@S, LEN(@S)-1);  --LEFT is to remove comma at the end

WITH CTE AS(
SELECT CAST( (SELECT CAST( col1 AS varchar(10))+ ','
               FROM @Test b 
				FOR XML PATH('')
				) AS VARCHAR(MAX)) concat_string
		)
SELECT STUFF(concat_string,1,1,'')
FROM CTE

WITH CTE AS(
SELECT CAST( (SELECT CAST( col1 AS varchar(10))+ ','
               FROM @Test b 
				FOR XML PATH('')
				) AS VARCHAR(MAX)) concat_string
		)
SELECT STUFF(concat_string,1,1,'')
FROM CTE

,2,3,4,5,6,7,1,4,5,

WITH CTE AS(
SELECT CAST( (SELECT CAST( col1 AS varchar(10))+ ','
               FROM @Test b 
				FOR XML PATH('')
				) AS VARCHAR(MAX)) concat_string
		)
SELECT STUFF(concat_string,1,1,'')
FROM CTE

,2,3,4,5,6,7,1,4,5,

WITH CTE AS(
SELECT CAST( (SELECT  ',' + CAST( col1 AS varchar(10))               FROM @Test b 
				FOR XML PATH('')
				) AS VARCHAR(MAX)) concat_string
		)
SELECT STUFF(concat_string,1,1,'')
FROM CTE