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Question

源码：
protected void Button1_Click(object sender, EventArgs e)
    {
        string conStr = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + Server.MapPath(".") + "\\Data\\user.mdb";
        conn = new OleDbConnection(conStr);
        conn.Open();
        string strSql = "select * from user_reg where username='" + username.Text + "'and '" + userpwd.Text + "'";
        cmd = new OleDbCommand(strSql,conn);
        dr = cmd.ExecuteReader();
        if (dr.Read())
        {
            Response.Redirect("exam.aspx");
            conn.Close(); 
        }
        else
        {
            Label1.Text = "请重新输入";
        }
    }
输入用户和密码后，不能转到exam.aspx这页面，这是怎么回事呢？

Answer 1

发漏一点代码
 protected void Button1_Click(object sender, EventArgs e)
    {
        string conStr = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + Server.MapPath(".") + "\\Data\\user.mdb";
        conn = new OleDbConnection(conStr);
        conn.Open();
        string strSql = "select * from user_reg where username='" + username.Text + "'and userpwd='" + userpwd.Text + "'";
        cmd = new OleDbCommand(strSql,conn);
        dr = cmd.ExecuteReader();
        if (dr.Read())
        {
            Response.Redirect("exam.aspx");
            conn.Close(); 
        }
        else
        {
            Label1.Text = "请重新输入";
        }
        dr.Close();
    }

Answer 2

试试这个
private void btnSubmit_Click(Object sender,EventArgs e )
{
String url = null;
String ConnStr = "Provider=Microsoft.JET.OLEDB.4.0;DATA SOURCE=C:\\database.mdb";
using(System.Data.OleDb.OleDbConnection conn = new System.Data.OleDb.OleDbConnection(ConnStr))
{
System.Data.OleDb.OleDbDataReader dr = null;
try
{
String QueryStr = "SELECT * FROM ....................................................";
System.Data.OleDb.OleDbCommand cmd = new System.Data.OleDb.OleDbCommand(QueryStr,conn);
conn.Open();
dr = cmd.ExecuteReader(System.Data.CommandBehavior.SingleRow);
if(dr.Read())
url = "exam.aspx";
}
catch(Exception ex)
{
// thow new Exception or Response.Write(ex.ToString());
}
finally
{
conn.Close();
conn.Dispose();
if(dr!=null)
{
dr.Close();
dr = null;
}
}
} if( url!=null )
{
Response.Redirect(url);
Response.End();
} 
else 
{
this.lbl1.Text = "请重新输入";
}
}//end of btnSubmit
象你这样写用户登录实在是不可取,极其不安全

Answer 3

try..string conStr = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + Server.MapPath(".") + "\\Data\\user.mdb";
            conn = new OleDbConnection(conStr);
            conn.Open();
            string strSql = "select * from user_reg where username='" + username.Text.Trim() + "'and userpwd='" + userpwd.Text.Trim() + "'";
            cmd = new OleDbCommand(strSql, conn);
            dr = cmd.ExecuteReader();
            if (dr.Read())
            {
                Response.Redirect("exam.aspx");
                conn.Close();
            }
            else
            {
                Label1.Text = "请重新输入";
            }
            dr.Close();
            conn.Close();

Answer 4

或者试试这个:string conStr = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + Server.MapPath(".") + "\\Data\\user.mdb";
            conn = new OleDbConnection(conStr);
            conn.Open();
            string strSql = "select count(*) from user_reg where username='" + username.Text.Trim() + "'and userpwd='" + userpwd.Text.Trim() + "'";
            cmd = new OleDbCommand(strSql, conn);
            int count = Convert.ToInt32(cmd.ExecuteScalar());
            if (count > 0)
            {
                Response.Redirect("exam.aspx");
                conn.Close();
            }
            else
            {
                Label1.Text = "请重新输入";
            }
            conn.Close();

Answer 5

debug是很重要的工具。
F5,设置断点。F10一步一步来