Hi can someone explain what is this 'nest_left' and 'nest_right' columns in database. There is no explain in documentation. I have records in database now and i add this 2 columns to my database but now i dont know how should i filled this columns in existing records. I tried to filled my records like this: I filled nest_left and nest_right with unique integer numbers and sorting work but when i tried to update some records i have error: "Illegal operator and value combination." Could someone explain what is this two columns and how filled when i have existing records and why i have this error?

ok it solved. If someone want to know what mean this columns can read: https://en.wikipedia.org/wiki/Nested_set_model