A master detail form displays a master row and multiple detail rows within a single HTML form. With this form, users can insert, update, and delete values from two tables or views.
A master detail form reflects a one-to-many relationship between two tables in a database.
See first Oracle Apex - Tabular Form
When running a master detail form, data is rendered as a report using various form elements (including text fields, text areas, date pickers, select lists, radio groups, and so on).
On the Master Detail:
The Create Page Wizard provides support for creating a master detail from two tables that do not have foreign key relationship defined in the database.