I'm working on a Winforms C# application for a client which replaces their old MS Access based solution. It's a complete rewrite and now uses SQL Server as its database. This software is now in the final stages of development.
One thing that they've just requested is that ability to do custom queries that the software's UI may not currently let them do at the time they need it.
With their old Access solution, they could use the query designer to create their own custom queries. With the winforms/Sql Server solution they can't do this. They don't want to have to write SQL themselves either.
Can anyone think of a good solution to this problem? Perhaps a Winforms library which allows the user to create a graph of business objects and "and|or" logic. Or some other type of UI which allows them to customise queries, almost like they could do in Access (but perhaps more domain specific).
Update
I've flagged Yaqub's answer as the answer, as this is the closest to what I was looking for at the time. I ended up though writing a custom form for them to generate their queries:
The "Select table ..." combobox in the second group only shows tables that have been added to the top listbox.
Because the database layout is pretty much set in stone now, I've written code to intelligently calculate any joins required. For example, if they add two indirectly related tables in the top group, then when it generates the SQL, it'll add any required joins to relate those. If the database layout does change, I've made it very easy to change FK references in the query editor's code.
For the condition group, the value control (4th control down in that group) changes depending on the field type (textbox, numerical up/down control, datepicker, checkbox).
When they click on "Run query", they get another form with a gridview displaying th