How to check that user enters only digits

IsNumeric() function returns true for a string, which can me converted to number, like "1 2", "1e2". But if you need to check that string contains only digits? The simplest way I think is:

If strVar Like String(Len(strVar),"#") then
       'Only numbers!
End If

MSysConf table

This system table is not very known, but it offers 2 unique possibilities:

• It can disable the feature that enables users to save the logon ID and password for a linked SQL database in the Microsoft Access front end.
• It can optimize how Microsoft Access performs background population of records during idle time by setting the number of rows of data that are retrieved at one time and the number of seconds of delay between each retrieval. Microsoft Access uses a default of 100 records that are returned every 10 seconds if you don't create the MSysConf table.

Do not try to find it in you mdb, unlike other system tables you have to create it by yourself, in SQL server database. All details on table structure and configuration options you can find at About using the MSysConf table to optimize your linked SQL database (MDB) and at How to store SQL database login IDs and passwords locally.