Test...
sqlite> insert into tree values (1,0,1,4,"dir");
--my first node
sqlite> insert into tree values (2,1,2,1,"file");
--my first guest
sqlite> insert into tree values (3,0,3,4,"dir2");
--my second node
sqlite> select * from tree;
1|0|1|4|dir
2|1|2|1|file
3|0|3|4|dir2
sqlite> update tree...