Best validation for MySQLi insert completed ?

Hello,
We have a form that is suffering from validations NOT catching various inputs people are entering.

No errors stop the page from moving to $WA_redirectURL

I'm surprised the MySQL DB does not throw an error but it seems not to be the case.

One of the prior found errors was a vachar field that was 14 characters in size but the person entered 15 characters. This caused the record not to be submitted but there was no error that stopped the page from moving to it's $WA_redirectURL location.

Is there a value we should poll before moving to the redirect page?

I understand we should have page level validation and we do, but since we don't get these errors stopping the flow it's hard to track down where problems exist.