MySQL 5.7

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SELECT t.*, 
       @rownum := @rownum + 1 AS row_number
  FROM (   SELECT 111 AS `group_id`
                UNION ALL 
                SELECT 111 AS `group_id`
                UNION ALL 
                SELECT 111 AS `group_id`
                UNION ALL 
                SELECT 111 AS `group_id`
                UNION ALL 
                SELECT 111 AS `group_id`
                UNION ALL 
                SELECT 111 AS `group_id`
                UNION ALL 
                SELECT 111 AS `group_id`
                UNION ALL 
                SELECT 111 AS `group_id`
                UNION ALL 
                SELECT 111 AS `group_id`
                UNION ALL 
                SELECT 222 AS `group_id`
                UNION ALL 
                SELECT 222 AS `group_id`
                UNION ALL 
                SELECT 222 AS `group_id`
                UNION ALL 
                SELECT 222 AS `group_id`
                UNION ALL 
                SELECT 333 AS `group_id`
                UNION ALL 
                SELECT 333 AS `group_id`
				) t, 
       (SELECT @rownum := 0) r

group_id	row_number
111	1
111	2
111	3
111	4
111	5
111	6
111	7
111	8
111	9
222	10
222	11
222	12
222	13
333	14
333	15

group_id	row_number
111	1
111	2
111	3
111	4
111	5
111	6
111	7
111	8
111	9
222	10
222	11
222	12
222	13
333	14
333	15

group_id	row_number
111	1
111	2
111	3
111	4
111	5
111	6
111	7
111	8
111	9
222	10
222	11
222	12
222	13
333	14
333	15

group_id	row_number
111	1
111	2
111	3
111	4
111	5
111	6
111	7
111	8
111	9
222	10
222	11
222	12
222	13
333	14
333	15