Can the visitor be presented with a "collapsing" database table?
What do you mean by collapsing table? Do you want to collapse the table use .collapse and .expand on the table. If you want like an FAQ collapsable interface that’s another thing. Try to describe more and attach a screenshot.
I want to show table from "datset" but to show only the title's row, and to expand it by click
This is not supported in tables but might be accomplished with coding but will require some amount of skills to be done. Maybe this would be a feature request?