Ask the pre-sort traversal tree algorithm (non-recursive infinite-pole classification algorithm), delete a branch node and all of its child nodes related issues

Ask the pre-sort traversal tree algorithm (non-recursive infinite-pole classification algorithm) to delete a branch node and all of its child nodes



Delete a branch node and all of its child nodes, see a piece of code from the Internet, and find this to be wrong,
Please ask, how to write SQL, thank you!
------to solve the idea----------------------

Delete from food where lft>= current node lft and RGT <= current node RGT

------to solve the idea----------------------
UPDATE nested_category SET lft = lft-@myWidth WHERE lft > @myRight
should be for
UPDATE nested_category SET lft = lft-@myWidth WHERE lft > @myLeft

