Displaying a Datagrid with a related filed column

I have a base select query that I am trying to reproduce using GC functions. I am having an issue displaying the related field COLUMN because the match fields are not the primary key in the relationship.

Here is the query:

SELECT 
a.`ID_Account` as "Account #",
a.`Account` as "Account",
a.`Phone1` as "Phone",
a.`Email` as "Email",
c.`Name_First` as "First Name",
c.`Name_Last` as "Last Name",
a.`Account_Type` as "Account Type",
a.`Status` as "Status"

FROM `fsc_ACC_Accounts` a

LEFT JOIN fsc_CON_Contacts c ON a.`ID_Account` = c.`id_account` AND c.`flag_primary` = 1

Can someone assist me? Thanks in advance.