C#实现签到+1 要使用什么控件

天 前面是一个label 怎么能让他 点完签到 label 数值加1
我写的代码会报错说DATAtime。。。。
private void button1_Click(object sender, EventArgs e)
{
string days = (int.Parse(this.label2.Text)+ 1 ).ToString();
SqlConnection conn = new SqlConnection("Data Source=PC201405231508;Initial Catalog=salary;Integrated Security=True");
string sql = "update staff_salary set T_monthworkdays='" + days + "' where num=(select num from worker where work_user='" + use + "')";
conn.Open();
SqlCommand cmd = new SqlCommand(sql, conn);
if (cmd.ExecuteNonQuery() == 1)
{
string sql1 = "select * from staff_salary where num=(select num from worker where work_user='" + use + "')";
SqlCommand cmd1 = new SqlCommand(sql1, conn);
SqlDataReader dr = cmd1.ExecuteReader();
while (dr.Read())
{
this.label2.Text = dr["T_monthworkdays"].ToString();
this.button1.Enabled = false;
this.button2.Enabled = false;
}
conn.Close();
MessageBox.Show("签到成功");
}
}

你还可以用label的tag属性保存数值

label就行了，把label的text转为int，加一后，再转为string显示