我正在从网站上执行预约功能。它可以比较日期&创建新约会之前的时间,如果用户键在同一日期&时间存在于数据库中,则会弹出消息框。当我尝试插入不同于db的日期&时,它给我错误。 Errorc#未将对象引用设置为对象的实例
我得到错误在这条线:
string dtime = time.ExecuteScalar().ToString();
我不知道什么是错我的代码,任何人都可以点我吗?谢谢。 这是我的代码:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;
using System.Configuration;
using System.Windows.Forms;
public partial class MakeAppointment : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Button1_Click(object sender, EventArgs e)
{
string appointmentdate = Convert.ToString(DropDownListDay.Text + "-" + DropDownListMonth.Text + "-" + DropDownListYear.Text);
string appointmenttime = Convert.ToString(DropDownListHour.Text + ":" + DropDownListMinute.Text + ":" + DropDownListSecond.Text + " " + DropDownListSession.Text);
SqlConnection con = new SqlConnection("Data Source=USER-PC;Initial Catalog=webservice_database;Integrated Security=True");
con.Open();
SqlCommand date = new SqlCommand("Select adate from customer_registration where adate='"+ appointmentdate +"'",con);
string ddate = date.ExecuteScalar().ToString();
con.Close();
if (ddate == appointmentdate)
{
con.Open();
SqlCommand time = new SqlCommand("Select atime from customer_registration where atime='"+ appointmenttime +"'", con);
string dtime = time.ExecuteScalar().ToString();
con.Close();
if (dtime == appointmenttime)
{
MessageBox.Show("This appointment is not available. Please choose other date & time.");
}
}
}
在哪一行,你得到的错误? – MBen
您确定数据库中的adate'字段不为空吗?我认为它抛出了一个异常,因为'adate'为空 – saber
@MBen对不起,我编辑我的文章,并包括错误,我有错误的字符串dtime = time.ExecuteScalar()。 – Ching