If ORDER BY is not given, the rows are returned in whatever order the system finds fastest to produce. If the ORDER BY clause is specified, the returned rows are sorted in the specified order. (See UNION Clause, INTERSECT Clause, and EXCEPT Clause below.) Notice that DISTINCT is the default behavior here, even though ALL is the default for SELECT itself. The noise word DISTINCT can be added to explicitly specify eliminating duplicate rows. In all three cases, duplicate rows are eliminated unless ALL is specified. The EXCEPT operator returns the rows that are in the first result set but not in the second. The INTERSECT operator returns all rows that are strictly in both result sets. The UNION operator returns all rows that are in one or both of the result sets. Using the operators UNION, INTERSECT, and EXCEPT, the output of more than one SELECT statement can be combined to form a single result set.

SELECT ALL (the default) will return all candidate rows, including duplicates.

SELECT DISTINCT ON eliminates rows that match on all the specified expressions. SELECT DISTINCT eliminates duplicate rows from the result. The actual output rows are computed using the SELECT output expressions for each selected row or row group. (See GROUP BY Clause and HAVING Clause below.) Although query output columns are nominally computed in the next step, they can also be referenced (by name or ordinal number) in the GROUP BY clause. If the HAVING clause is present, it eliminates groups that do not satisfy the given condition. If the GROUP BY clause is specified, or if there are aggregate function calls, the output is combined into groups of rows that match on one or more values, and the results of aggregate functions are computed. If the WHERE clause is specified, all rows that do not satisfy the condition are eliminated from the output. (Each element in the FROM list is a real or virtual table.) If more than one element is specified in the FROM list, they are cross-joined together. (See WITH Clause below.)Īll elements in the FROM list are computed. A WITH query that is referenced more than once in FROM is computed only once, unless specified otherwise with NOT MATERIALIZED. These effectively serve as temporary tables that can be referenced in the FROM list. SET cycle_mark_col_name USING cycle_path_col_name ]Īll queries in the WITH list are computed.

Postgresql update join group by