LATERAL JOINs & Row-by-Row Operations: Concept

LATERAL allows subquery to reference columns from preceding tables. Executes subquery for each row. Like correlated subquery but in FROM clause.

LATERAL enables row-by-row operations. Subquery can reference outer query columns. Useful for top-N per group, complex calculations. SQL Server uses CROSS APPLY/OUTER APPLY.

LATERAL joins solve complex problems elegantly. Essential for advanced SQL developers. Supported in PostgreSQL, Oracle, SQL Server (CROSS APPLY).

Get top 3 products per category. Find latest 5 orders per customer. Retrieve most recent status per entity. LATERAL enables row-by-row correlated operations.