Using SQLite

Transaction Control Language

The Transaction Control Language is used in conjunction with the Data Manipulation Language to control the processing and exposure of changes. Transactions are a fundamental part of how relational databases protect the integrity and reliability of the data they hold. Transactions are automatically used on all DDL and DML commands.

ACID Transactions

A transaction is used to group together a series of low-level changes into a single, logical update. A transaction can be anything from updating a single value to a complex, multistep procedure that might end up inserting several rows into a number of different tables.

The classic transaction example is a database that holds account numbers and balances. If you want to transfer a balance from one account to another, that is a simple two-step process: subtract an amount from one account balance and then add the same amount to the other account balance. That process needs to be done as a single logical unit of change, and should not be broken apart. Both steps should either succeed completely, resulting in the balance being correctly transferred, or both steps should fail completely, resulting in both accounts being left unchanged. Any other outcome, where one step succeeds and the other fails, is not acceptable.

Typically a transaction is opened, or started. As individual data manipulation commands are issued, they become part of the transaction. When the logical procedure has finished, the transaction can be committed, ...