OK I built something because also I wanted to experiment with databases and switches. I use SQLite because it provides a simple DB. You might switch that out.
What it does it lists all the databases table1 - table4. Three tables have the column “sales” one does not. The Loop would extract all structures from every table and see if a column “sales” is there. If yes the DB would be loaded, if not the database is skipped.
It uses Vernalis nodes and also an old entry from Iris.
kn_example_sqlite_skip_missing_column.knwf (113.4 KB)