“SqlParameterCollection only accepts non-null SqlParameter type objects, not String objects”

Question

I keep getting the exception

The SqlParameterCollection only accepts non-null SqlParameter type objects, not String objects

, while execut

Answer 1

When you use Add method, you are trying to add a new parameter. What you want to do is to assign value. So change this:

comm.Parameters.Add(dataGridView1.Rows[i].Cells[0].Value.ToString());

to this:

comm.Parameters["@author"].Value = dataGridView1.Rows[i].Cells[0].Value.ToString();

Similarly for the other parameters.