DataGridView失去焦点的问题，麻烦高手解答，谢谢

我希望在点归还这个按键的时候（fillByreadToolStripButton_Click），除了将borrow表中删除一条记录 还希望同时在book和readers表中坐修改
请问该如何做，我以下的代码有时会删错行的数据，有时无法删除，我该怎么修改呢？？
amespace Library
{
    public partial class ghbook : Form
    {
        public ghbook()
        {
            InitializeComponent();
        }
        //String read = "";
        //String bh = "";                private void ghbook_Load(object sender, EventArgs e)
        {
            // TODO: 这行代码将数据加载到表“libraryDataSet.borrow”中。您可以根据需要移动或移除它。
            this.borrowTableAdapter.Fill(this.libraryDataSet.borrow);            //read=this.borrowDataGridView.CurrentRow.Cells[0].Value.ToString();
            //bh = this.borrowDataGridView.CurrentRow.Cells[1].Value.ToString();
        }        private void fillByreadToolStripButton_Click(object sender, EventArgs e)
        {
            try
            {
                this.borrowTableAdapter.FillByread(this.libraryDataSet.borrow, readersbhToolStripTextBox.Text);
            }
            catch (System.Exception ex)
            {
                System.Windows.Forms.MessageBox.Show(ex.Message);
            }        }        private void bindingNavigatorDeleteItem_Click(object sender, EventArgs e)
        {
            try
            {                this.Validate();                String conn = "Dsn=Library;uid=sa;pwd=261903659;app=Microsoft® Visual Studio® 2005;wsid=TT;database=Library";
                OdbcConnection connstring = new OdbcConnection(conn);                MessageBox.Show(this.borrowDataGridView.CurrentRow.Cells[0].Value.ToString());
                //修改readers表中已经借了几本书的值使其 -1
                String sqlchange = "UPDATE readers set yjsl=yjsl-1 where BH='" + this.borrowDataGridView.CurrentRow.Cells[0].Value.ToString() + "'";
                OdbcCommand comm1 = new OdbcCommand(sqlchange, connstring);
                connstring.Open();
                comm1.ExecuteNonQuery();
                connstring.Close();                MessageBox.Show(this.borrowDataGridView.CurrentRow.Cells[1].Value.ToString());                //修改book表中置状态为 归还
                String sqlchange2 = "UPDATE book set zt='归还' where bh='" + this.borrowDataGridView.CurrentRow.Cells[0].Value.ToString() + "'";
                OdbcCommand comm2 = new OdbcCommand(sqlchange2, connstring);
                connstring.Open();
                comm2.ExecuteNonQuery();
                connstring.Close();
                this.borrowBindingSource.EndEdit();
                this.borrowTableAdapter.Update(this.libraryDataSet.borrow);                MessageBox.Show("书籍归还成功！");
            }
            catch
            {
                MessageBox.Show("归还失败！");
            }
        }        private void fillByToolStripButton_Click(object sender, EventArgs e)
        {
            try
            {
                this.borrowTableAdapter.FillBy(this.libraryDataSet.borrow);
            }
            catch (System.Exception ex)
            {
                System.Windows.Forms.MessageBox.Show(ex.Message);
            }        }