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SQL Program 50: Rollback a change

Praveen KulkarniPraveen Kulkarni

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CS TECHIIE | SQL Notes and Solutions

Practical SQL exercise: Cancels uncommitted changes in a transaction.

Objective

Cancels uncommitted changes in a transaction.

Explanation

Read the statement clause by clause and predict the result before executing it. These examples use common relational SQL; table setup and exact syntax can vary between MySQL, PostgreSQL, SQL Server, Oracle and SQLite.

Safety check

Before running UPDATE or DELETE, run a SELECT with the same WHERE condition. Use a test database and a transaction for changes you need to verify.

Program / SQL Solution

BEGIN; UPDATE products SET price=price*1.10; ROLLBACK;

Practice and revision

  • Run the example and verify the output.
  • Change the input and test normal, boundary and invalid cases.
  • Write the solution again without looking at the notes.

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