Question

Microsoft’s own documentation provides an example of deleting a record as follows:

// Create the DeleteCommand.
command = new SqlCommand(
    "DELETE FROM Customers WHERE CustomerID = @CustomerID", connection);

// Add the parameters for the DeleteCommand.
parameter = command.Parameters.Add(
    "@CustomerID", SqlDbType.NChar, 5, "CustomerID");
parameter.SourceVersion = DataRowVersion.Original;

adapter.DeleteCommand = command;

But on my system it doesn’t work (complaining about missing @CustomerID). Instead, if I replace the

command.Parameters.Add("@CustomerID", SqlDbType.NChar, 5, "CustomerID");

above with

command.Parameters.AddWithValue("@CustomerID", 5);

It works.

Why?

Answer 1

In this line:

command.Parameters.Add("@CustomerID", SqlDbType.NChar, 5, "CustomerID");

In this overload, 5 refers to the length of the parameter, not the value. If you want to add the value, you’ll have to add the following:

command.Parameters["@CustomerID"].Value = "5";