What are Cursors and why are they usually discouraged?

Quick Answer Cursors iterate over result sets one row at a time. For large datasets this is extremely slow â€” it bypasses SQL Server's set-based engine. Most cursor logic can be rewritten with set-based updates, window functions, or CTEs. Use cursors only when row-by-row processing is genuinely unavoidable, like calling a stored procedure per row.

Answer

Cursors are database objects that allow row-by-row traversal of a result set, similar to iterators in procedural languages.

Reasons they are discouraged:

They process data one row at a time, leading to poor performance on large sets.
They often hold locks for a long time, reducing concurrency.
They introduce complex, procedural logic that is harder to maintain and test.
They typically have higher memory and tempdb overhead compared to set-based alternatives.

Cursors should be a last resort, used only when set-based solutions are impractical or impossible. In many cases, window functions, MERGE statements, or carefully written set-based updates can replace cursor logic.

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What are Cursors and why are they usually discouraged?

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