Understanding the Use of Transaction Command in MySQL

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Transactions are a crucial part of dealing with data in any database. In MySQL, transactions allow us to bundle several SQL queries into a single unit of work. By doing so, we can ensure that our database remains in a consistent state, even when things go wrong. But just like any other aspect of programming, the devil is in the details. So, let's take a closer look at transactions in MySQL.

Transaction Command

A transaction is a sequence of one or more SQL commands that are treated as a logical unit. This means that all the commands within a transaction are either all executed or none of them are. The power of this comes from its ability to maintain data integrity even if a part of the transaction fails.

Here's an example of a transaction in MySQL:

START TRANSACTION;
UPDATE accounts SET balance = balance - 100 WHERE name = 'John';
UPDATE accounts SET balance = balance + 100 WHERE name = 'Jane';
COMMIT;

This transaction transfers $100 from John's account to Jane's. If any part of the transaction fails (let's say John doesn't have enough money), none of the transactions are executed. That's the power of the transaction command in MySQL.

Transaction Control Statements

MySQL uses four transaction control statements: START TRANSACTION, COMMIT, ROLLBACK, and SET AUTOCOMMIT.

• START TRANSACTION begins a new transaction.
• COMMIT makes the changes done in the transaction permanent.
• ROLLBACK undoes the changes made in the transaction.
• SET AUTOCOMMIT disables or enables the autocommit mode for the current session. By default, every single MySQL command is a complete transaction on its own.

FAQ

START TRANSACTION;
UPDATE accounts SET balance = balance - 100 WHERE name = 'John';
UPDATE accounts SET balance = balance + 100 WHERE name = 'Jane';
COMMIT;