又一个错误,急
这个是DB类
using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
using System.Data.OleDb;
/// <summary>
/// db 的摘要说明
/// </summary>
public class db //: System.Web.UI.Page
{
public db()
{
//
// TODO: 在此处添加构造函数逻辑
//
}
public static OleDbConnection Conn_2(string dbName)
{//数据库连接类
OleDbConnection Conn2 = new OleDbConnection(ConfigurationManager.ConnectionStrings[dbName].ConnectionString);
return Conn2;
}
public static DataSet ds_2(string que, string dbNameView,string dbName)
{//返回一个装载了SQL制定的数据表,
OleDbConnection Conn = db.Conn_2(dbName);
OleDbDataAdapter oda = new OleDbDataAdapter();
oda.SelectCommand = new OleDbCommand(que, Conn);
DataSet ds = new DataSet();
oda.Fill(ds, dbNameView);
return ds;
}
}
这个是调用代码
dbName = "Provider = Microsoft.Jet.OLEDB.4.0; Data Source =" + System.Web.HttpContext.Current.Server.MapPath("default/sskeyial/menu.mdb");
//int id;
string sql = "select * from menu where id1=" + id + " order by id1,id";
DataSet ds = db.ds_2(sql, "menu", dbName);
错误提示
未将对象引用设置到对象的实例。
说明: 执行当前 Web 请求期间,出现未处理的异常。请检查堆栈跟踪信息,以了解有关该错误以及代码中导致错误的出处的详细信息。
异常详细信息: System.NullReferenceException: 未将对象引用设置到对象的实例。
源错误:
dbName = "Provider = Microsoft.Jet.OLEDB.4.0; Data Source =" + System.Web.HttpContext.Current.Server.MapPath("default/sskeyial/menu.mdb");
//int id;
string sql = "select * from menu where id1=" + id + " order by id1,id";
DataSet ds = db.ds_2(sql, "menu", dbName);
怎么错了,不明白?