Penanganan pengecualian spesifik dan pesan

Transaksi dan Penanganan Error di PostgreSQL

Jason Myers

Principal Engineer

Menangani tipe pengecualian tertentu

DO $$
BEGIN
    UPDATE inventory SET quantity = quantity - 1 WHERE name in ('flour', 'sugar');
EXCEPTION
    WHEN check_violation THEN
           INSERT INTO errors (msg) VALUES ('Quantity can not be less than 0.');
           RAISE INFO 'Quantity can not be less than 0.';
END; 
$$ language 'plpgsql';

Output dari penanganan pengecualian kita

INFO:  Quantity can not be less than 0.
DO
postgres=# select * from errors;
 error_id | state |               msg                | detail | context
^---------+-------+----------------------------------+--------+---------
        1 |       | Quantity can not be less than 0. |        |
(1 row)

Jenis kondisi pengecualian yang umum

Condition Name	Example
unique_violation	Menyisipkan dua nilai yang sama di kolom unik
not_null_violation	Menyisipkan null ke kolom yang tidak mengizinkan null
check_violation	Gagal pada constraint check, mis. nilai “deliciousness” > 11
division_by_zero	Membagi dengan 0

Masih banyak lagi pada tautan di sitasi di bawah

¹ https://www.postgresql.org/docs/9.4/errcodes-appendix.html

Menangani beberapa pengecualian

DO $$
BEGIN
    UPDATE inventory SET quantity = quantity - 6, cost = null 
    WHERE name='oatmeal dark chocolate';

Menangani beberapa tipe pengecualian secara terpisah

-- Tambahkan pengecualian check_violation
EXCEPTION
  WHEN check_violation THEN
     INSERT INTO errors (msg) VALUES ('Quantity can not be less than 0.');
     RAISE INFO 'Quantity can not be less than 0.';

-- Tambahkan pengecualian not_null
  WHEN not_null_violation THEN
     INSERT INTO errors (msg) VALUES ('Cost can not be null.');
     RAISE INFO 'Cost can not be null.';
END; $$ language 'plpgsql';

Output penanganan beberapa pengecualian

INFO:  Cost can not be null.
DO
postgres=# select * from errors;
 error_id | state |               msg                | detail | context
^---------+-------+----------------------------------+--------+---------
        2 |       | Cost can not be null.            |        |
(1 row)

Saatnya menerapkan!

Transaksi dan Penanganan Error di PostgreSQL