If the database is MS SQL Server, look into creating SQL that checks your date column for the appropriate criteria and then use CDO/CDOSYS/CDONTS (depending) to shoot out the email.
I didnt get involved with SQL Mail on SQL Server for various reasons, but you may want to look into that anyhow.
And, depending on if this date check is happening on the fly (as records are added, updated) then you may want to utilize a trigger (MS SQL Server) and run the SQL from the trigger. If you're looking to schedule it every X often, then look into the SQL Server Agent and its Job functionality.
is a great resource from which I learned a good deal from.
If you're using MS Access or MySQL, I think you'll find similar facilities (no triggers in Access I dont think) and if Oracle then you'll find many similarities to MS SQL Server. Not too sure about MySQL but it looks to be somewhere in between Access and SQL Server in terms of Triggers and Job Scheduling.
The SQL itself is whatever you'd write to satisfy your date selection criteria and should execute against any database relatively unchanged except for each implementations date formatting.
Hope that helps a bit, good luck!