Problem with deleting and update grid rows

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C#

ASP.NET

Hello everyone

I write some webapp and i must use grid view with deleting and edit button.
I try write deleting function :

try
           {


               connectionString = cnn;
               sqlConnection = new SqlConnection(connectionString);
               sqlConnection.Open();
               SqlCommand cmdDelete = new SqlCommand();
               string Delete = "DELETE FROM Teacher_Major WHERE Teacher_Major.major_id=@id";
               cmdDelete.Connection = sqlConnection;
               cmdDelete.CommandText = Delete;
               int id = int.Parse(gvMajor.Rows[e.RowIndex].Cells[1].Text.ToString());
               cmdDelete.Parameters.AddWithValue("@id", id);
               cmdDelete.ExecuteNonQuery();

           }
           catch (Exception exceptionObj)
           {

           }

but this return error :

Deleting is not supported by data source 'SqlDataSource1' unless DeleteCommand is specified.

How i can fix this ?
Thnx for help