MaskedEdit in Ajax To0lKit... take a look

MaskedEditExtender is an ASP.NET AJAX extender that attaches to a TextBox control to restrict the kind of text that can be entered. the supported data formats are: Number, Date, Time, and DateTime

MaskedEditValidator is a custom validator which attaches to the MaskedEdit extender and its associated TextBox and verifies that the input text matches the pattern specified in the MaskedEdit extender.

to get more information please take a look at the following link

http://www.asp.net/AJAX/AjaxControlToolkit/Samples/MaskedEdit/MaskedEdit.aspx

Difference Between Count(*) and Count(1) in SQL

Both will be same in terms of performance, as the execution is to retrieve information from the table. You are free to use any constant expression instead of * - you can use COUNT(0), COUNT('a') and even COUNT(NULL) - each with the same results. You can also use a column name as the parameter, but this means that rows with a NULL on that column will not be counted The 'normal' parameter for COUNT is * - in most cases there is no reason to use anything else

Difference between First() && Single() in LINQ

The difference between First() and Single() methods in LINQ is that First grabs the first item it finds. The Single method expects only a single matching item and will throw an exception if it finds more than one. it is very semi note about the difference and i am preparing a lot about the LINQ and i will publish it in the Following Posts very sooon ... Waaaaaaaaaaaaaaaaaaaaaaiting