When your extension needs some database tables then you can define this tables in the extension editor. On each update or installation of your extensions the system installs or alters the tables for you.

1.

In this section you can insert the table name. With the button + you can add new fields and with the button - you can remove this table.

2.

This section contains all fields. Each field has several inputs:

• Name
  This is the field name.
• Type
  This is the field type
• Length
  The length of the field. Required when type is 'varchar', or optiona when type is 'int'.
• Options
  Some field options like is Primary, is Index or Fulltext (search).
• AI, Autoincrement (Sequence)
  If auto incremented with the mysql AUTO_INCREMENT or with other engines the SEQUENCES.

DB-Update

Before you press this button you should press the Save button to save your entries. The DB-Update button simulate a extension update/install. So all table definition from your extension goes to the database.