Do You Have Your Own RegEXp To Validate Your String

I just realized that it's so important to validate each string, I mean
'each' before you insert data from asp page into database.

I guess some customers just copy data from some electronic document and
paste intoform field which it will probably mess up the program.

for example, we have a customer who wants to enter AH12345 into one of our
fields, it appears Ð?Ð?12345 in hidden field of our asp page, but it displayed
AH12345 to the customer, but our program failed because of the data does fit
into char field in sql database.

I don't know in reality, how other companies deal with those kind of thing.
Do I have write our own regExp to validate each string, since we do need to
allow apostrophe or "-" in first name or last name.