multiple column to onec column

[zab08 <zab08@xxxxxxx>]

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,

& nbsp;role2      | permission1

for short:

afer join of two table, here is some repeat columns,

I only want to a row for role1.