SQL WHERE filters individual rows before grouping, while HAVING filters aggregated groups after GROUP BY.
SQL WHERE applies row-level filters before grouping; HAVING applies group-level filters after GROUP BY. Choose WHERE for base conditions and HAVING for aggregated conditions.
WHERE evaluates each row before any aggregation. HAVING evaluates the result of GROUPBY, letting you filter groups created by aggregate functions. Because HAVING runs later in the execution order, it can reference aliases and aggregates that WHERE cannot.
Use WHERE when you need to restrict raw rows. Example: filter orders by status='completed' before you calculate revenue. Placing the filter early reduces data processed downstream and speeds query execution.
Use HAVING when you must filter on aggregate results such as SUM, COUNT, AVG, MAX, or MIN. Example: return only product categories with COUNT(order_id)>100. HAVING lets you keep or discard entire groups based on aggregate thresholds.
Yes, but it is rarely needed. Without GROUP BY, HAVING behaves like WHERE on an aggregated result set of one row. Use WHERE instead unless you require HAVING for stylistic consistency or complex subqueries.
SQL executes clauses in the logical order: FROM → WHERE → GROUPBY → HAVING → SELECT → ORDERBY. Knowing this sequence prevents logic errors and improves performance. Attempting to use aggregates in WHERE fails because aggregates are calculated later.
Galaxy’s AI copilot flags misuse of HAVING or WHERE as you type. It suggests moving filters to the correct clause and auto-completes aggregate expressions. Built-in query linting ensures your team shares optimized, error-free SQL in Galaxy Collections.
Apply non-aggregate filters in WHERE to reduce rows early, then use HAVING for aggregate thresholds. Avoid placing all conditions in HAVING—it slows queries. Comment complex logic, and in Galaxy, endorse the final query so teammates reuse the vetted pattern.
The following query filters completed orders first, then filters categories with total sales above $10,000.SELECT category,
SUM(total_amount) AS category_sales,
COUNT(order_id) AS orders
FROM orders
WHERE status = 'completed'
GROUP BY category
HAVING SUM(total_amount) > 10000;
If you see "invalid column" or "aggregate function not allowed," verify that the column exists in the source tables or that aggregates appear only in HAVING. In Galaxy, hover over the error underline for an instant explanation and fix suggestion.
Placing aggregates in WHERE, forgetting GROUPBY columns, or overusing HAVING can break queries. Move aggregates to HAVING, ensure each selected non-aggregated column is grouped, and push simple conditions to WHERE for performance gains.
Understanding HAVING vs WHERE prevents logic bugs that silently skew metrics. Using WHERE for raw filters cuts scan size, saving compute costs. Applying HAVING correctly allows precise business rules like "only show profitable stores." Mastery leads to maintainable, performant queries your team can trust.
Yes in most cases. HAVING executes after grouping, so filtering earlier with WHERE reduces data first and speeds execution.
Absolutely. Use WHERE for row-level filters and HAVING for group-level filters in the same query.
You’ll get an error in strict SQL modes. Move that condition to WHERE or GROUP BY.
Galaxy’s SQL linter warns when aggregates appear in WHERE or when simple filters sit in HAVING, offering one-click fixes.