You will find that the table and field name is not displayed for some fields, mostly totals and prices. One example is the document total field in marketing documents. In a document this field is concatenated with the currency symbol, whereas in the database the amount and currency are stored in different columns. Therefore this field does not exist in the database.
You can still run a query using these fields, you just need to look up the field name in the query tool. An easy way to do this is to create a document, then run a query on the table and select all fields.