How to concatenate strings of a string field in a PostgreSQL 'group by' query?

Question

I am looking for a way to concatenate the strings of a field within a group by query. So for example, I have a table:

ID   COMPANY_ID   EMPLOYEE
1    1               


        

Answer 1

According to version PostgreSQL 9.0 and above you can use the aggregate function called string_agg. Your new SQL should look something like this:

SELECT company_id, string_agg(employee, ', ')
    FROM mytable GROUP BY company_id;