pgSQL的WITH和RECURSIVE是什么意思??高分求教!!!
公司有一条SQL语句写的是:
WITH RECURSIVE r AS (
SELECT * FROM test1 as t WHERE m_id = 18
union ALL
SELECT t.* FROM trade.merchant as t, r WHERE tree.par = r.m_id
)
SELECT * FROM r where stat = 1 ORDER BY m_id
实在是看不懂,上网找了找介绍WITH、和RECURSIVE的教程,都没讲的细的,就官方手册讲的全点,但我英文不好~
能大概介绍一下(最好有个小例子)这俩命令怎么用吗?另外它里面的t.*是什么意思?
谢谢!