private void btnEdit_Click(object sender, EventArgs e)
        {
            if (txtID.Text == "")
            {
                MessageBox.Show("请选择要修改的记录");
                return;
            }
            linq = new linqtosqlClassDataContext(strCon);//实例化Linq连接对象
            //查找要修改的员工信息
            var result = from employee in linq.tb_Employee
                         where employee.ID == txtID.Text
                         select employee;

            //对指定的员工信息进行修改
            foreach (tb_Employee tbemployee in result)
            {
                tbemployee.Name    = txtName.Text;
                tbemployee.Sex     = cboxSex.Text;
                tbemployee.Age     = Convert.ToInt32(txtAge.Text);
                tbemployee.Tel     = txtTel.Text;
                tbemployee.Address = txtAddress.Text;
                tbemployee.QQ      = Convert.ToInt32(txtQQ.Text);
                tbemployee.Email   = txtEmail.Text;
                linq.SubmitChanges();
            }
            MessageBox.Show("员工信息修改成功");
            BindInfo("");
        }
        private void btnDel_Click(object sender, EventArgs e)
        {
            if (txtID.Text == "")
            {
                MessageBox.Show("请选择要删除的记录");
                return;
            }
            linq = new linqtosqlClassDataContext(strCon);//实例化Linq连接对象
            //查找要删除的员工信息
            var result = from employee in linq.tb_Employee
                         where employee.ID == txtID.Text
                         select employee;

            linq.tb_Employee.DeleteAllOnSubmit(result); //删除员工信息
            linq.SubmitChanges();                       //实例化Linq连接对象提交操作
            MessageBox.Show("员工信息删除成功");
            BindInfo("");
        }
        private void btnAdd_Click(object sender, EventArgs e)
        {
            linq = new linqtosqlClassDataContext(strCon); //实例化Linq连接对象
            tb_Employee employee = new tb_Employee();     //实例化tb_Employee类对象

            //为tb_Employee类中的员工实体赋值
            employee.ID      = txtID.Text;
            employee.Name    = txtName.Text;
            employee.Sex     = cboxSex.Text;
            employee.Age     = Convert.ToInt32(txtAge.Text);
            employee.Tel     = txtTel.Text;
            employee.Address = txtAddress.Text;
            employee.QQ      = Convert.ToInt32(txtQQ.Text);
            employee.Email   = txtEmail.Text;
            linq.tb_Employee.InsertOnSubmit(employee); //添加员工信息
            linq.SubmitChanges();                      //提交操作
            MessageBox.Show("员工信息添加成功");
            BindInfo("");
        }