SQL Clause Referencia
Referencia para SQL consulta clauses: SELECT, FROM, WHERE, GROUP BY, HAVING, ORDER BY, LIMIT.
Query Structure and Order
SQL clauses have a logical evaluation order: FROM -> WHERE -> GROUP BY -> HAVING -> SELECT -> DISTINCT -> ORDER BY -> LIMIT/OFFSET. The written order differs: SELECT first, then FROM, WHERE, etc. FROM identifies source tables and joins. WHERE filters rows before grouping. GROUP BY groups rows by expressions. HAVING filters groups after aggregation. SELECT chooses columns and computes expressions. ORDER BY sorts. LIMIT/OFFSET paginate. Understanding logical order clarifies alias scope and aggregation.
- WHERE
- Pre-group filter
- HAVING
- Post-group filter
- ORDER BY
- Sort results
row-levelgroup-levelASC/DESCAdvanced Clauses
FETCH FIRST n ROWS ONLY is the standard alternative to LIMIT (SQL:2008). OFFSET for pagination. RETURNING (PostgreSQL/Oracle) returns affected rows. FOR UPDATE locks rows for update. WITH (CTE) defines named subqueries before the main query. OVER clause defines window function partitioning and framing. FILTER clause (SQL:2003) selectively aggregates. GROUPING SETS, ROLLUP, CUBE produce multiple grouping levels in one query. QUALIFY (Snowflake, BigQuery) filters window function results.
- FETCH FIRST
- Standard LIMIT
- RETURNING
- Get affected rows
- WITH/CTE
- Named subquery
SQL:2008INSERT/UPDATE/DELETEbefore main query