Muhammad al-xorazmiy nomidagi toshkent axborot texnologiyalari universiteti mustaqil-1-2-3-4-5

Rollback amalini bajarilishi
-- Begin Transaction
BEGIN;

-- Savepoint

SAVEPOINT before_complex_query;

BEGIN TRY

-- Complex query, you can replace this with your actual query
UPDATE Products
SET price = price * 1.1
WHERE category = 'Electronics';

-- Simulate an error, for example, a constraint violation

INSERT INTO Products (name, category, price) VALUES ('New Product', 'Clothing', 25.99);
EXCEPTION
-- If an error occurs, rollback to the savepoint
WHEN OTHERS THEN
ROLLBACK TO SAVEPOINT before_complex_query;
-- Optionally handle or log the error
RAISE NOTICE 'An error occurred: %', SQLERRM;
END TRY;

-- If no error occurred, commit the transaction

COMMIT;

-- Mijozlarni o'zgartirish

UPDATE customers
SET email = '[e-mail]'
WHERE last_name = 'Smith' AND phone_number LIKE '+998%';

-- Buyurtmalarni o'zgartirish

UPDATE orders
SET total_amount = 2000
WHERE customer_id IN (SELECT customer_id FROM customers WHERE last_name = 'Smith');


SAVEPOINT tranzaksiyasini ishlatilishi
-- Begin Transaction
BEGIN;

-- Savepoint

SAVEPOINT before_complex_transaction;

BEGIN TRY

-- Complex transaction, you can replace this with your actual logic
-- Update prices of products in the 'Electronics' category
UPDATE Products
SET price = price * 1.1
WHERE category = 'Electronics';

-- Savepoint

SAVEPOINT after_price_update;

-- Insert a new product

INSERT INTO Products (name, category, price) VALUES ('New Product', 'Clothing', 25.99);

-- Commit the transaction

COMMIT;
EXCEPTION
-- If an error occurs, rollback to the savepoint
WHEN OTHERS THEN
ROLLBACK TO SAVEPOINT after_price_update;
-- Optionally handle or log the error
RAISE NOTICE 'An error occurred: %', SQLERRM;
-- Rollback the entire transaction (excluding the price update)
ROLLBACK TO SAVEPOINT before_complex_transaction;
END TRY;