The window
clause allows to centralize and reuse window definitions. It is the last clause of <table expression>
—i.e. it follows the having
clause if present.
SELECT MIN(x) OVER window_name
, MAX(x) OVER window_name
FROM …
[ WHERE … ]
[ GROUP BY … ]
[HAVING … ]
WINDOW window_name AS ([PARTITION BY …] [ORDER BY …] …)
Both window functions, min
and max
, use the same window definition.
Other forms: over
clause (inline), window … as (<existing window name> …)
Product specific clause: qualify
.
The window
clause is defined in ISO/IEC 9075:2016-2 as part of optional feature T612, “Advanced OLAP operations”.
You can’t catch up on 20 years of SQL evolution in one day. Subscribe the newsletter via E-Mail, Twitter or RSS to gradually catch up and to keep modern-sql.com on your radar.
The essence of SQL tuning in 200 pages
Buy now!
(paperback and/or PDF)
Paperback also available at Amazon.com.
Markus offers SQL training and consulting for developers working at companies of all sizes.
Learn more »