I've recently come accross some strange behavior in an access database that has been kicking along (unmodified) just fine for a couple of years. After digging into a nested query that held a few joins, I could not for the life of me figure out why it was not joining correctly. It was not making joins that it clearly should be. To test, I recreated the top level query from scratch (even the SQL text matched exactly) and the recreated query performed perfectly. Blew my mind... Obviously there was some corruption with at least that query. Since the recreated query worked fine, I figured the data was fine. I was concerned that other queries might be suffering the same fate and I wanted to further test the issue, so I ran a Compact and Repair. I opened up the database and went to the same troubled query, only to find that now it performed correctly. (I can repeat this with the same results - pre and post compact) What bothers me is there was no corruption noted when opening the database, and really no way to tell something was wrong until someone noticed some data that didn't appear quite right. Essentially, I realy could have gone years without knowing an issue existed. How can I identify this? I don't find an acceptable solution to be simply performing a daily compact and repair. Where is the integrety in Access (I'm an SQL dba). Was this simply a corrupt index in access? How can I tell if there are problems without waiting for it to come out in the data itself. I'm just seriously concerned about data integrity now with this small database (100MB) - any ideas, suggestions, encouragement? Help! Thanks!