Query the tree structure of MySQL

ID	PID
1	-1
2	-1
3	1
4	1
5	1
6	2

In the above table, the PID is the parent node of the ID.-1 indicates the root node. If you want to query all the nodes in the tree where a node is located (except the root node), for example, check 1, so we should return 1, 3, 4, 5; check 3, also return 1, 3, 4, 5; The following is the query SQL, although a little tedious, I do not know how efficient, we can still find out which brother has a simple method.

Select * from table where id = $ ID or pid = (select PID from table where id = $ ID and PID <>-1) or Id = (select PID from table where id = $ ID and PID <>-1)