CREATE TABLE saldo (
    id BIGINT NOT NULL,
    uid INTEGER,
    VALUE NUMERIC(12,2),
    currency CHARACTER(3)
);

CREATE SEQUENCE saldo_id_seq
    START WITH 1
    INCREMENT BY 1
    NO MAXVALUE
    NO MINVALUE
    CACHE 1;
  ALTER TABLE ONLY saldo ALTER COLUMN id SET DEFAULT NEXTVAL('saldo_id_seq'::regclass);

ALTER TABLE ONLY saldo
    ADD CONSTRAINT saldo_id_key UNIQUE (id);

$saldo = $Db->PREPARE("
        WITH update_outcome AS(
            UPDATE saldo
            SET value=value+ :value
            WHERE uid=:uid AND currency=:currency
        ),
        insert_outcome AS (
            INSERT INTO
                saldo
            (uid, value, currency)
            SELECT
                :uid2 AS uid,
                :value2 AS value,
                :currency2 AS currency
            WHERE NOT EXISTS (SELECT id FROM saldo WHERE uid= :uid3 AND currency= :currency3 LIMIT 1)
        )");
        $saldo->bindParam(':uid', $uid, PDO::PARAM_INT);
        $saldo->bindParam(':value', $_SESSION['throw'], PDO::PARAM_STR, 8);
        $saldo->bindParam(':currency', $_SESSION['currency'], PDO::PARAM_STR, 3);
        $saldo->bindParam(':uid2', $uid, PDO::PARAM_INT);
        $saldo->bindParam(':value2', $_SESSION['throw'], PDO::PARAM_STR, 8);
        $saldo->bindParam(':currency2', $_SESSION['currency'], PDO::PARAM_STR, 3);
        $saldo->bindParam(':uid3', $uid, PDO::PARAM_INT);
        $saldo->bindParam(':currency3', $_SESSION['currency'], PDO::PARAM_STR, 3);    
        $saldo->EXECUTE();