C# 取ACCESS字段

我如果先要对表中XH字段做一下判断,然后写一个温馨的对话框提示用户XH字段值为0，那字段XH该怎么取出来呢? 大家帮忙看看！ 谢谢了，源代码如下，数据库已连接
C# code:

OleDbConnection conn = new OleDbConnection();
conn.ConnectionString = "Provider = Microsoft.Jet.OleDb.4.0;" + "Data Source =" + Server.MapPath("**.mdb");
sting xh;
if()
{????}
string updateStr = "update zhuanjia set [xh] = xh-1 where [id] = " + Convert.ToInt32(Request["id"]);

OleDbCommand insCom = new OleDbCommand(updateStr, conn);

conn.Open();

insCom.ExecuteNonQuery();
conn.Close();

---

那当然得用查询出来呀,

---

access的操作
C# code:
和连接sql2005差不多,只需要该连接字符串即可.

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Data.OleDb;
using System.Data.SqlClient;

namespace TestAccess
{
class Program
{
static void Main(string[] args)
{
#region Access 2007
Console.WriteLine("Access 2007");
string strConnection = "Provider=Microsoft.ACE.OLEDB.12.0;";
strConnection += @"Data Sour