If there are several SQL statements in the editor, make sure to separate them using the statement delimiter character (the default is ";").
In order for the column name completion pop-up to appear, you must first make sure there are table names in the statement.
All table names that have been listed in the completion pop-up are cached by DbVisualizer to make sure subsequent displays of the pop-up is performed quickly without asking the database. The cache is cleared only when doing a Refresh in the database objects tree or reconnecting the database connection.
The Database and Schema lists above the editor are used to limit the list of tables in the auto complete pop-up to those in the selected database and/or schema. To include all tables, select the blank entries in these lists. The default selections for the lists can be set in the as connection properties, in the SQL Commander category.