Updating External data links automaticly without opening the Workbook

[custy]

Hi There

I have a workbook that is linked to 4 SQL database tables that I would like to be able to have update automatically, say at a specific time or after a specified period, without having to open the file. The SQL data sources are password protected, so I assume VBA will be my only option, if it is even possible, and I am looking for some pointers to start with

Thanks