W3cubDocs

/MariaDB

WITH

The WITH keyword signifies a Common Table Expression (CTE). It allows you to refer to a subquery expression many times in a query, as if having a temporary table that only exists for the duration of a query.

There are two kinds of CTEs:

MariaDB starting with 10.2.1

Common Table Expression WITH was introduced in MariaDB 10.2.1.

MariaDB starting with 10.2.2

Recursive WITH has been supported since MariaDB 10.2.2.

Syntax

WITH [RECURSIVE] table_reference as (SELECT ...)
  SELECT ...

You can use table_reference as any normal table in the external SELECT part. You can also use WITH in sub queries. WITH can also be used with EXPLAIN and SELECT.

Below is an example with the WITH at the top level:

WITH t AS (SELECT a FROM t1 WHERE b >= 'c') 
  SELECT * FROM t2, t WHERE t2.c = t.a;

The example below uses WITH in a subquery:

SELECT t1.a, t1.b FROM t1, t2
  WHERE t1.a > t2.c 
     AND t2.c IN(WITH t AS (SELECT * FROM t1 WHERE t1.a < 5)
                SELECT t2.c FROM t2, t WHERE t2.c = t.a);

Below is an example of a Recursive CTE:

WITH RECURSIVE ancestors AS 
 ( SELECT * FROM folks
   WHERE name="Alex"
   UNION
   SELECT f.*
   FROM folks AS f, ancestors AS a
   WHERE f.id = a.father OR f.id = a.mother )
SELECT * FROM ancestors;

See also

Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.

© 2019 MariaDB
Licensed under the Creative Commons Attribution 3.0 Unported License and the GNU Free Documentation License.
https://mariadb.com/kb/en/with/