The selectTree render type is used to display hierarchical data in a tree structure.

A field with the selectTree render type allows you to represent data in a hierarchical manner, similar to a tree. It is typically used when working with database tables that have a hierarchical structure. The properties treeConfig and foreign_table are mandatory and must be provided to establish the connection to the relevant database table. Optionally, you can also use items or itemsProcFunc to pass the values, but these are not sufficient on their own. The top-level item in the tree will always represent the descriptive name of the table.

Regarding joining several tables, the selectTree render type can handle multiple tables through the configuration options.