'No overload for method 'ToString' takes '1' arguments' error occur While Formatting Datetime Field To String ON "dd-MM-yyyy" format
You need to cast it to DateTime first:
DateTime leave = (DateTime) rdMonthlyLeave["LEAVE_DATE"];DoSomethingWith(leave.ToString("dd-MM-yyyy"));or just
((DateTime)rdMonthlyLeave["LEAVE_DATE"]).ToString("dd-MM-yyyy")The return type of the DataReader indexer is just object, and object doesn't have an overload of ToString which takes a string. Don't forget that overloading is a compile-time decision - the compiler picks the appropriate method with a compatible signature, and only overriding occurs based on the execution-time type. In this case there is no overload of ToString with a compatible signature, so you get a compile-time error.