If you are retrieving or adding values from and to your database then you will know the difficulties that can be caused by NULL values. The notorious InvalidCastException is one example of receiving a NULL value from your database into an ASP.NET object that doesn’t know what to do with database NULL values.
Here’s typical example of an InvalidCastException error caused by setting a String variable to a value that is returned as a NULL from your database query:
System.InvalidCastException: Conversion from type 'DBNull' to type 'String' is not valid. at Microsoft.VisualBasic.CompilerServices.Conversions.ToString(Object Value) at ASP.myPageName_aspx.Page_Load(Object sender, EventArgs e) in D:\Inetpub\wwwroot\MySite\myPageName.aspx:line 1xx
If you find this article useful, have a look at some of the other ASP.NET tips and tricks articles I’ve published. Continue reading “ASP.NET – Handling Null Return Values from the Database using IsDBNull”