Question

I have integrated Jstree in my application, now i want to understand different column in that table:

CREATE TABLE IF NOT EXISTS `tree` (
  `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
  `parent_id` bigint(20) unsigned NOT NULL,
  `position` bigint(20) unsigned NOT NULL,
  `left` bigint(20) unsigned NOT NULL,
  `right` bigint(20) unsigned NOT NULL,
  `level` bigint(20) unsigned NOT NULL,
  `title` text CHARACTER SET utf8 COLLATE utf8_unicode_ci,
  `type` varchar(255) CHARACTER SET utf8 COLLATE utf8_unicode_ci DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=utf8 AUTO_INCREMENT=13 ;

This is the default table provided by the site.

Now if want to add a node, how do i know the value for left, right and level.

Answer 1

This looks like a mix of Adjacency list an nested sets.

Nested sets are a better way of storing trees in a relational database.
It’s hard to explain the principle you have to look here and here.

When you use nested sets you don’t need parent_id.
I think jstree provided a sample table where you can choose by yourself what technique you use.

Another way of storing trees in a database would be a Closure Table.
It’s my personal favourite. It’s simple but powerful. But you hardly find anything about it on the net.