I'm looking for a decent tool we can give to a few key users to allow them to design queries for themselves against our production database. It won't be feasible to get these guys actually writing sql but they'll understand the data-structure so we can probably get away with giving them a tool similar to the query designer that's in SQL Server Management Server. I'm not comfortable giving them management studio, though, and I don't want them to be able to update the tables or data in any way.

Can anyone offer up any recommendations? It needs to be:-
1. Easy to use
2. Secure (it would be nice if it connected as an application user to make it easy for us to control the security in the back end)
3. Able to separate update permissions from reads