Delete images from the ACCESS database,image as a filter

 string sql = "DELETE* from picInfo where pic=@img";
 DBHelper.OpenConnection();//DBHelper is a class with a method OpenConnection and a method Connection
OleDbCommand comm = new OleDbCommand(sql, DBHelper.Connection);

//here is the key sentence .
 comm.Parameters.Add("@img", OleDbType.VarBinary, ((byte[])dataGridView.SelectedCells[0].Value).Length).Value =dataGridView.SelectedCells[0].Value;            
comm.ExecuteNonQuery();