comma separated string of selected values in mysql

Question

I want to convert selected values into a comma separated string in MySQL. My initial code is as follows:

SELECT id FROM table_level where parent_id=4;
         


        

Answer 1

First to set group_concat_max_len, otherwise it will not give you all the result:

SET GLOBAL  group_concat_max_len = 999999;
SELECT GROUP_CONCAT(id)  FROM table_level where parent_id=4 group by parent_id;