Database records can be specified using variables when the “Specify record by variable” option is enabled (columns cannot be used).
I’m implementing a dialogue system using a database in a conversation sample, but after adding elements like nameplates and character sprites, it has become quite complicated, so it may not be very helpful as an example…
A smarter approach would be to use Dialogic, a Godot plugin for creating dialogue scenes, which can also be used with AGMaker. This might be a good option.