SQL SELECT: Difference between revisions
Jump to navigation
Jump to search
| Line 9: | Line 9: | ||
</font> | </font> | ||
Almost every query will include at least three of these clauses (<code>[[#SELECT|SELECT]]</code>, <code>[[#FROM|FROM]]</code> and <code>[[#WHERE|WHERE]]</code>). | |||
Upon execution, an SQL query returns a [[SQL#Result_Set|result set]]. | Upon execution, an SQL query returns a [[SQL#Result_Set|result set]]. | ||
Revision as of 23:18, 22 May 2024
Internal
Overview
A query consists in at least one (SELECT) and at most six categories of clauses:
SELECT [...] FROM [...] WHERE [...] GROUP BY [...] HAVING [...] ORDER BY [...];
Almost every query will include at least three of these clauses (SELECT, FROM and WHERE).
Upon execution, an SQL query returns a result set.
Select all (possibly across multiple tables) then filter and discard with where.
Example
SELECT id, name FROM person WHERE id = 1;
The following query:
SELECT;
is valid, it returns one empty row.
Clauses
SELECT
FROM
FROM permanent|derived|temporary|virtual(view)
Table alias.