I have an interesting one. I am important an Excel sheet where one column is a telephone number such as 506-111-2222. This is pretty much all the format we have in this column. But, two rows contain the 911 number. As this one doesn't contain any special characters and only digits, it is aligned right, making it a number. When importing that into a dataset, as the first row is having the proper format, this will be defined as a character field. But, for those two rows where 911 is indicated, because they are considered a number in Excel, this will be recognized as DBNull.Value.

So, if the best practice to ask the user to adjust the Excel sheet? But, if yes, what exactly should I ask him for as far as adapting the layout. As those are valid phone numbers. But, they are entered as is.