ADO.NET C# common error dealing with inserting NULL value

If you are using c# and you are trying to insert null value into a table by using a shorthand something like below

param.Add("@abc", strAbc == "" ? null : strAbc);

it will not work. And you will got this error such as below:

Parameterized Query '(@Type nvarchar(2),@GroupType nvarchar(1),@Keyword' expects parameter @Type, which was not supplied.

To solve this problem you need to do a trick something like this

param.Add("@abc", strAbc == "" ? (object)DBNull.Value : strAbc);

change from null to (object)DBNull.Value

However, in VB.NET you do not need to cast.