mysql8.0递归

sql举例：

WITH recursive c1 AS( 
	select * from course_category  where id = '1-1'
	union all
	select t2.* from course_category t2 INNER JOIN c1  where t2.parentid=c1.id
		
)
select * from c1 ORDER BY orderby;

解释：

WITH recursive c1 AS( //相当于创建了一个虚拟表
    select * from course_category  where id = '1-1'   //虚拟表的第一条数据
    union all
    select t2.* from course_category t2 INNER JOIN c1  where t2.parentid=c1.id
     //递归的语句，从这个表和虚拟表联表查询
)
select * from c1 ORDER BY orderby;//查出虚拟表中想要的数据