//班级表的单元格单击事件
        private void dataGridView4_CellContentClick(object sender, DataGridViewCellEventArgs e)
        {
            //选中行的图书编号
            int str = -1;

            try
            {
                str = (int)dataGridView4.Rows[e.RowIndex].Cells[0].Value;
            }
            catch (Exception) { }

            //DataGridView的总列数
            int rows = dataGridView4.Columns.Count;

            if (e.ColumnIndex == rows - 2)//修改
            {
                Class c = new Class();
                c.ClassId   = str;
                c.ClassName = dataGridView4.Rows[e.RowIndex].Cells[1].Value.ToString();
                Edit_UI exit = new Edit_UI();
                exit.aa   = this;
                exit.c    = c;
                exit.Text = "修改班级";
                exit.ShowDialog();
            }
            else if (e.ColumnIndex == rows - 1)//删除
            {
                DialogResult result = MessageBox.Show("确定删除吗?", "提醒", MessageBoxButtons.OKCancel, MessageBoxIcon.Question);
                if (result == DialogResult.OK)
                {
                    if (class_bll.deleteClass(str) > 0)
                    {
                        this.dataGridView4.DataSource = class_bll.selectClass1().Tables[0];
                    }
                    else
                    {
                        MessageBox.Show("删除失败!");
                    }
                }
            }
        }
        //用户类型表的单元格单击事件
        private void dataGridView2_CellContentClick(object sender, DataGridViewCellEventArgs e)
        {
            //选中行的图书编号
            int str = -1;

            try
            {
                str = (int)dataGridView2.Rows[e.RowIndex].Cells[0].Value;
            }
            catch (Exception) { }

            //DataGridView的总列数
            int rows = dataGridView2.Columns.Count;

            if (e.ColumnIndex == rows - 2)//修改
            {
                UserType r = new UserType();
                r.UserTypeId   = str;
                r.UserTypeName = dataGridView2.Rows[e.RowIndex].Cells[1].Value.ToString();
                Edit_UI exit = new Edit_UI();
                exit.aa   = this;
                exit.r    = r;
                exit.Text = "修改用户类型";
                exit.ShowDialog();
            }
            else if (e.ColumnIndex == rows - 1)//删除
            {
                DialogResult result = MessageBox.Show("确定删除吗?", "提醒", MessageBoxButtons.OKCancel, MessageBoxIcon.Question);
                if (result == DialogResult.OK)
                {
                    if (readerType_bll.deleteUser(str) > 0)
                    {
                        this.dataGridView2.DataSource = readerType_bll.selectUserType1().Tables[0];
                    }
                    else
                    {
                        MessageBox.Show("删除失败!");
                    }
                }
            }
        }