SQL删除命令

当我删除一条记录时，它工作了。但是当我关闭程序并再次打开它时，实际上记录并没有被删除。

private void button5_Click(object sender, EventArgs e) 
{
        SqlConnection con = new SqlConnection();
        con.ConnectionString = @"Data Source=.'SQLEXPRESS;AttachDbFilename=D:'Upper_Stage_Data.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True";
        con.Open();
        MessageBox.Show("Delete Current Row of Database Open");
        if (MaxRows != 0)
        {
            SqlCommand Command = new SqlCommand("DELETE FROM Table1 WHERE Data_no='@inc'", con);
            try
            {
                Command.ExecuteNonQuery();
                MessageBox.Show("Record Deleted");
            }
            catch (SqlException)
            {
                MessageBox.Show("ERROR: Could not delete record");
            }
            MaxRows--;
            if (inc != 0)
            {
                inc--;
                NavigationRecords();
            }
            else
            {
                if (MaxRows != 1)
                {
                    inc++;
                    NavigationRecords();
                }
                else
                {
                    MessageBox.Show("No Record");
                }
            }
        }
        else
        {
            MessageBox.Show("No Record");
        }
        con.Close();
        MessageBox.Show("Delete Current Row of Database Closed");
        con.Dispose();
}

当我搜索时，有些记录不能被删除，因为它们是"主"记录。我怎样才能真正删除记录?

SqlCommand Command = new SqlCommand("DELETE FROM Table1 WHERE Data_no=@inc", con);

Command.Parameters.AddWithValue("@inc", inc); //inc is a variable that contain a value for the @inc parameter