How to insert null in datetime type column in sql server

Question

I have a table in which there are some datetime type columns. I use a stored procedure to insert values into the table. In the stored procedure I have variables that accept null

Answer 1

You should just be able to supply null directly as a parameter value:

if (String.IsNullOrWhitespace(InsertDate.Text)) {
    cmd1.Parameters["@InsertDate"].Value = null;
} else {
    cmd1.Parameters["@InsertDate"].Value = InsertDate.Text;
}

Also switched to using String.IsNullOrWhitespace() to check for an empty string.