How would you create a database in Microsoft Access that is searchable only by certain fields and controlled by only a few (necessary) text boxes and check boxes on a form so it is easy to use – no difficult queries?
Example: You have several text boxes and several corresponding check boxes on a form, and when the check box next to the text box is checked, the text box is enabled and you can then search by what is entered into said text box
(Actually I already know this, just playing stackoverflow jeopardy, where I ask a question I know the answer just to increase the world’s coding knowledge! answer coming in about 5 mins)
This is actually a pretty large topic, and fraught with all kinds of potential problems. Most intermediate to advanced books on Access will have some kind of section discussing ‘Query by Form,’ where you have an unbound form that allows the user to choose certain criteria, and that when executed, writes on-the-fly SQL to return the matching data.
In anything but a flat, single-table data structure, this is not a trivial task because the FROM clause of the SQL is dependent on the tables queried in the WHERE clause.
A few examples of some QBF forms from apps I’ve created for clients:
The first one is driven by a class module that has properties that reflect the criteria selected in this form, and that has methods that write the FROM and WHERE clauses. This makes it extremely easy to add other fields (as long as those fields don’t come from tables other than the ones already included).
The most complex part of the process is writing the FROM clause, as you have to have appropriate join types and include only the tables that are either in the SELECT clause or the WHERE clause. If you include anything else, you’ll slow down your query a lot (especially if you have any outer joins).
But this is a big subject, and there is no magic bullet solution — instead, something like this has to be created for each particular application. It’s also important that you test it thoroughly with users, since what is completely clear and understandable to you, the developer, is often pretty darned mystifying to end users.
But that’s a principle that doesn’t just apply to QBF!