If the date doesn't have the four-digit year, it's needs to be changed so that the full year is represented. When looking at a date in a spreadsheet or database file we also need to determine if the date is stored in a date format . On the other hand, if the information is stored in a date format, it is likely that when you convert the field so that it must display using the full 8-digit format, the application will make a guess at the proper century. These applications will examine the 2-digit year used in the date string and, depending on how close it is to the current date, will attempt to apply the correct century. Obviously, a century mask will not work for all date conversions, so use caution - some files will need to be converted or corrected manually .
Lets take a look at some common date formating problems.
Our example applications will be Microsoft's Excel and Access. In the example below we see a few rows of information in a common spreadsheet format. This means that the information contained in these cells is in text format - the system doesn't recognize the cell information as dates. Because the field is in text format , we run the risk of introducing even more errors - the user could type in letters, symbols, or impossible dates, because Excel will not restrict the information that should be entered there. If no selection was highlighted when you opened the Format Cells window, it means that the selected cells have different formats.