postgres身份證15位轉18位

CREATE OR REPLACE FUNCTION idcard15to18("card" varchar)
    RETURNS varchar AS $$
DECLARE
    RESULTS varchar(18);
    W       INTEGER ARRAY[18]; --數字數組
    A       CHAR ARRAY[11]; --字元數組
    S       Integer;
Begin
    If CARD Is Null Then
        Return '';
    End If;
    If LENGTH(CARD) <> 15 Then
        Return CARD;
    End If;
    W       := array[7, 9, 10, 5, 8, 4, 2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2, 1];
    A       := array['1', '0', 'X', '9', '8', '7', '6', '5', '4', '3', '2'];
    RESULTS := SUBSTR(CARD, 1, 6) || '19' || SUBSTR(CARD, 7, 10);
    S       := 0;
    Begin
        For I In 1 .. 17 Loop
            S := S + to_number(SUBSTR(RESULTS, I, 1),'9') * W[I];
        End Loop;
    Exception
        When Others Then
            Return '';
    End;
    S       := mod(S,11);
    RESULTS := RESULTS || A[S + 1];
    Return(RESULTS);
End;
$$ LANGUAGE plpgsql;

drop function idcard15to18(card varchar);