The Ultimate Guide to High Availability with MariaDB

WITH

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MariaDB starting with 10.2.1

Common Table Expression WITH was introduced in MariaDB 10.2.1.

Syntax

WITH [RECURSIVE] table_reference AS  (
  SELECT ...
)
[CYCLE cycle_column_list RESTRICT]
SELECT ...

Description

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:

You can use table_reference as any normal table in the external SELECT part. You can also use WITH in subqueries, as well as 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

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