sql连接时报错(急)
土衣 2007-08-28 03:48:53 在sqlcn.open()的时候报:"未将对象引用设置到对象实例",看了半天都不知道怎么回事,请高手指点,谢谢
代码如下:
using System;
using System.Data;
using System.Data.SqlClient;
using System.Windows.Forms;
namespace ddgl
{
/// <summary>
/// usercheck 的摘要说明。
/// </summary>
public class usercheck
{
public static SqlConnection sqlcn;
public static string connStr = "Initial Catalog=ddgldata;Data Source=(local);Integrated Security=SSPI;User ID='sa';password=''";
public usercheck()
{
}
public string UserSortCheck(string username,string userpassword)
{
sqlcn = new SqlConnection(connStr);
string txtSql;
string usersort="nobody";
//创建数据库连接
txtSql = "SELECT * FROM ddgluser";
SqlCommand checkuser=new SqlCommand(txtSql,sqlcn);
//创建SqlCommad
try
{
sqlcn.Open();
SqlDataReader sqlreader=checkuser.ExecuteReader();
while(sqlreader.Read())
{
if((sqlreader[0].ToString().Trim()==username)&&(sqlreader[1].ToString().Trim()==userpassword))
{
usersort=sqlreader[2].ToString().Trim();//返回用户类别
break;
}
}
}
catch(Exception e)
{
MessageBox.Show(e.ToString());
}
sqlcn.Close();
return usersort;
}
}
}