SQL---查询树中某个节点及其所有子节点
with f as ( select * from tab where id=1 union all select a.* from tab as a inner join f as b on a.pid=b.id ) select * from f
with f as ( select * from tab where id=1 union all select a.* from tab as a inner join f as b on a.pid=b.id ) select * from f