Database transaction
A group of database changes that all happen together or not at all.
A vending machine either takes your money and gives you the snack, or you keep your money. Nobody wants just one half. Moving stock from one warehouse to another is two updates. If the program crashes between them, stock vanishes. A transaction groups statements so they all happen, or none do. You commit to keep the changes, or roll back to undo them all. In Python,
with db:commits when the block ends and rolls back if an exception escapes.
Try it now
SQL runs in this order, not the order you write it, which explains many confusing errors.
Learn it properly
Databases and SQL · Store, query and join data with the language every database speaks. About 40 minutes.
Other terms from the same lesson
- foreign key: A column holding another table's primary key, which links the two rows, like an order's customer_id.
- primary key: A column that uniquely identifies each row of a table, such as an id.
- SQL: The language almost every database understands, for storing, finding, combining and summarizing data in tables.
- SQL injection: An attack where text pasted into a database query changes the query itself. Placeholders prevent it.
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