SQL doesn't have explicit 'for' or 'while' loops like programming languages. Instead, it uses `cursors` and `WHILE` statements to achieve looping behavior. These methods are less common than other SQL operations, but can be useful in specific scenarios.
SQL, unlike procedural languages like Python or Java, doesn't have built-in looping constructs like `for` or `while` loops. This is because SQL is primarily designed for set-based operations, where you work with entire datasets at once. However, there are ways to achieve iterative behavior. One common approach is using cursors, which allow you to process rows from a result set one at a time. Another method involves using `WHILE` statements in conjunction with conditions and updates. These methods are often less efficient than set-based operations and are typically used in specific situations where set-based solutions aren't feasible.
While not a primary feature, understanding cursors and `WHILE` loops is important for handling specific tasks that require processing data row by row, such as complex data transformations or updates based on intricate conditions.
SQL was created for declarative, set-based data manipulation, meaning you express what result you want over an entire table rather than describe step-by-step iteration. Because the query planner can operate on sets, it can optimize I/O, parallelize work, and use indexes efficiently. Procedural loops would break that model, so most SQL dialects omit native loop keywords and push users toward set operations such as JOINs, aggregations, and window functions.
Loops become necessary only in edge cases where each row must be handled sequentially—e.g., calling a stored procedure per row, performing complicated conditional logic, or interfacing with external systems. In these scenarios you can open a cursor to fetch one row at a time or use a WHILE loop that updates a control variable. Be aware these approaches are usually slower and harder to maintain than a single set-based statement.
Galaxy’s context-aware AI copilot suggests set-based rewrites, highlights anti-patterns like unnecessary cursors, and autocompletes JOIN or window-function syntax. By catching inefficiencies early and surfacing trusted, endorsed queries from your team, Galaxy lets you achieve the same business logic without resorting to WHILE loops—keeping your queries concise, performant, and easy to collaborate on.