SQL SELECT: Difference between revisions
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</font> | </font> | ||
The following query: | |||
<syntaxhighlight lang='sql'> | <syntaxhighlight lang='sql'> | ||
SELECT; | SELECT; | ||
</syntaxhighlight> | </syntaxhighlight> | ||
is | is valid, it 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 23:12, 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 [...]
The following query:
SELECT;
is valid, it 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)