Thank you for your post.
The easiest way is to set the Auto-enter options and have it filter out any non-numeric characters. That is, pull down the File menu and select "Manage -> Database..." Click on the Fields tab and select the field you want a numeric value. Click on Options, and under "Auto-Enter", put a check mark in "Calculated value". In the next screen, enter the formula:
Filter ( <numeric field in question> ; "0123456789" )
Click OK, and that should return you to the Auto-Enter options. Be sure to uncheck the option just below that "Do not replace existing value of field (if any)".
Click OK a couple of times, and now if you enter:
... and tab out of the field, the text is filtered out and leaves you with 5437.
You didn't mention which version of FileMaker Pro you are using, but if you are using FileMaker Pro 10, you can set up a script trigger so that each keystroke is captured and evaluated. If you need help with that, let me know.
you have to check 1 box in the validation options for that field:
1) numeric only
AND to uncheck 1 box:
2) Allow user to override during data entry
If you wish your own error message, check the box:
3) Display custom message if validation fais
you forgot that a numeric value can be negative and not integer.
Filter ( <numeric field in question> ; "-.,0123456789" )
You could also set the user's Access Privileges to 'Allow warning dialogue override = 'No', and then they will get the warning that says the data entry is invalid (so at least they know why it has been changed, or dis-allowed) but will not have any 'Yes' option to accept.
Edited: sorry, maybe my memory serves me wrong and I am only making the same point as raybaudi:
"AND to uncheck 1 box:
2) Allow user to override during data entry"
TSGal, raybaudi and sorbuster: all great and varied solutions to fix my problem - I learned a few new things from each of your recommendations.