Question

There is a SQL Server 2008 database for which I have to create a management software. The database contains a column named DateOfCreation. The table designer made this column as string and gave freedom to users to add date in any format they want and this was really a silly mistake by him. Now some users added as “24 Jan” or
“Jan 24” or “1991 1 12” and many unknown formats. What I want is that when I fetch this string date, a function should be called that will check the format and return -1 if date is not in correct format else return the converted date in DD/MM/YYYY. So how can I check the format of the date that string date variable is containing?

Answer 1

use DateTime.TryParseExact with your date format, it will return false in case if the date format is different or invalid.

For multiple formats you can specify multiple formats in a string array and then use that in DateTime.TryParseExact something like:

From MSDN – DateTime.TryParseExact Method (String, String[], IFormatProvider, DateTimeStyles, DateTime%)

string[] formats= {"M/d/yyyy h:mm:ss tt", "M/d/yyyy h:mm tt", 
                   "MM/dd/yyyy hh:mm:ss", "M/d/yyyy h:mm:ss", 
                   "M/d/yyyy hh:mm tt", "M/d/yyyy hh tt", 
                   "M/d/yyyy h:mm", "M/d/yyyy h:mm", 
                   "MM/dd/yyyy hh:mm", "M/dd/yyyy hh:mm"};
string[] dateStrings = {"5/1/2009 6:32 PM", "05/01/2009 6:32:05 PM", 
                        "5/1/2009 6:32:00", "05/01/2009 06:32", 
                        "05/01/2009 06:32:00 PM", "05/01/2009 06:32:00"}; 
DateTime dateValue;

foreach (string dateString in dateStrings)
{
   if (DateTime.TryParseExact(dateString, formats, 
                              new CultureInfo("en-US"), 
                              DateTimeStyles.None, 
                              out dateValue))
      Console.WriteLine("Converted '{0}' to {1}.", dateString, dateValue);
   else
      Console.WriteLine("Unable to convert '{0}' to a date.", dateString);
}