You could link the form to the table (creating a bound form) - set the Forms Recordsource to the name of the table and make sure each control on the form has the controlsource set to the underlying field.
If you have to use an unbound form then you can run the SQL in the forms AfterUpdate event.
Its more that the user will dump a new table into the db, the form will give the update query the name of this new table to update.
At present the query will run but doesnt know what table to run on, so i need to dynamically change the query based on the input from the text box.
The text box itself has no relationship with the table, except the name of it.
UPDATE Forms!frmtxt!txtbox, [IDN Switching] - You can only update one table at a time (the comma denotes a separate table - use FROM to join tables together)
SET Forms!frmtxt!txtbox.Idn1 = [IDN Switching].[Majority Holder] - in the Query desinger you can only reference a form for the value, not a field name. VBA is by far the better solution, the code i gave you is the basic outline of what you need: