SELECT
        cu.customer_id
        ,cu.customer_group
        ,cu.customer_code
        ,cu.customer_name1
        ,cu.customer_name2
        ,cu.status
        ,cu.note1
        ,CASE WHEN rgc.customer_code is null THEN 0 ELSE 1 END AS selected
    FROM 
        customer cu
        LEFT OUTER JOIN reading_group_customer rgc on
        	rgc.any_code = '31261001'
        	AND cu.customer_code = rgc.customer_code
    WHERE 
        cu.status <> -1
        AND cu.customer_group = '31261000'
    ORDER BY 
        cu.customer_id