SQL SELECT: Difference between revisions
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=Overview= | =Overview= | ||
A query consists in at least one (<code>[[#SELECT|SELECT]]</code>) and at most six categories of [[#Clauses|clauses]] | A query consists in at least one (<code>[[#SELECT|SELECT]]</code>) and at most six categories of [[#Clauses|clauses]]: | ||
<font> | <font> | ||
[[#SELECT|SELECT]] FROM WHERE GROUP BY HAVING ORDER BY | [[#SELECT|SELECT]] FROM WHERE GROUP BY HAVING ORDER BY | ||
</font> | </font> | ||
<syntaxhighlight lang='sql'> | |||
SELECT; | |||
</syntaxhighlight> | |||
is a valid query, returns one empty row. | |||
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 23:11, 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
SELECT;
is a valid query, returns one empty row.
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;
Clauses
SELECT
FROM
FROM permanent|derived|temporary|virtual(view)
Table alias.
Querying Multiple Tables
WHERE
GROUP BY ... HAVING
(make sure I understand thoroughly and link)