WHERE NOT EXISTS

<insert id="setInsertGiveCoupon">
    /* contractDAO.setInsertGiveCoupon */
    INSERT INTO th_cpn_hist
    (
        give_no
        , cpn_id
        , cust_id
        , use_yn 
        , frst_reg_dt
        , frst_rgtr_id
        , delete_yn 
    ) SELECT 
        (SELECT COALESCE(MAX(give_no::int4),0)+1 FROM th_cpn_hist)
        , #{give_cpn_id}
        , #{cust_id} 
        , 'N' 
        , now()
        , #{s_user_id} 
        , 'N'
        WHERE NOT EXISTS (
            select * from th_cpn_hist where cpn_id = #{give_cpn_id} and cust_id = #{cust_id} 		
        )
</insert>

UPDATE tn_coupon SET 
      cpn_nm 		= 'test1'
    , cpn_memo 		= '테스트22221'
    , cpn_ty_cd  	= '2' 
    , last_mod_dt	= now() 
WHERE cpn_id = '1' and not EXISTS (
   SELECT 1
   FROM   th_cpn_hist 
   WHERE  cpn_id = '1' and use_yn = 'Y'
);