[GENERAL] multiple column to onec column

[zab08]

I have two table:




CREATE TABLE roles(role_name varchar(255) primary key);


CREATE TABLE roles_permissions(permission varchar(100), role_name varchar(100));


here is result by :
 SELECT * from roles;
 role_name 
-----------
 role1
 role2
(2 rows)


here is result by :
SELECT * from roles_permissions ;
 role_name | permission  
-----------+-------------
 role1     | permission1
 role1     | permission2
 role2     | permission1
(3 rows)


---------------------------------------------------------------------------


after the command:
SELECT * from roles, roles_permissions;
 role_name | role_name | permission  
-----------+-----------+-------------
 role1     | role1     | permission1
 role1     | role1     | permission2
 role1     | role2     | permission1
 role2     | role1     | permission1
 role2     | role1     | permission2
 role2     | role2     | permission1




the expected result is:
 role_name | permission  
-----------+-------------
 role1      | permission1,permission2,
 role2      | permission1




for short:
afer join of two table, here is some repeat columns,


I only want to a row for role1.