[PostgreSql] 트랜잭션(Transaction)

1. 트랜잭션 설정.

BEGIN;

UPDATE accounts SET balance = balance - '1000000' WHERE name = 'Alice';

SAVEPOINT save_location;

UPDATE accounts SET balance = balance + '1000000' WHERE name = 'Bob';

ROLLBACK TO save_location;

UPDATE accounts SET balance = balance + '1000000' WHERE name = 'Sam';

COMMIT;

2. 전체 sql

DROP TABLE IF EXISTS accounts;

CREATE TABLE accounts (

  name VARCHAR(20) PRIMARY KEY,

  balance MONEY

);

INSERT INTO accounts VALUES('Alice', '5000000');

INSERT INTO accounts VALUES('Bob', '500000');

INSERT INTO accounts VALUES('Sam', '1000000');

BEGIN;

UPDATE accounts SET balance = balance - '1000000' WHERE name = 'Alice';

SAVEPOINT save_location;

UPDATE accounts SET balance = balance + '1000000' WHERE name = 'Bob';

ROLLBACK TO save_location;

UPDATE accounts SET balance = balance + '1000000' WHERE name = 'Sam';

COMMIT;

SELECT * FROM accounts;