从sql server获取asp.net中的记录时，它总是返回null [英] While fetching a record in asp.net from sql server it always return null

问题描述

从sql server中获取asp.net中的记录时，它总是返回null ..其代码 - 即使数据库中有记录，对象oid在运行时也会为null。请帮忙。谢谢。

 受保护  void  btnLogin_Click（  object  sender，EventArgs e）
 {
  string  cs = ConfigurationManager.ConnectionStrings [   DBMS]。ConnectionString; 
 SqlConnection con =  new  SqlConnection（cs）; 
 SqlCommand com =  new  SqlCommand（  select来自reg的id，其中user = @ user和password = @ pass，con）; 
 com.Parameters.AddWithValue（  @ user，txUName.Text）; 
 com.Parameters.AddWithValue（  @ pass，txPass.Text）; 
 con.Open（）; 
  var  oid = com.ExecuteScalar（）; 
 con.Close（）; 
 
  if （oid ==  null ）
 {
 lblEr.Visible =  true ; 
} 
  else  
 {
 Session.Add（  id，oid.ToString（））; 
 Session.Add（  user，txUName.Text）; 
 
 com =  new  SqlCommand（ 从dbo.reg中选择类型，其中user = @ u，con）; 
 com.Parameters.AddWithValue（  @ u，txUName.Text）; 
 con.Open（）; 
  var  otype = com.ExecuteScalar（）; 
 con.Close（）; 
 
  var  vtype =  管理员; 
  if （vtype == otype.ToString（））
 {
 Session.Add（  admin，otype.ToString（））; 
 Response.Redirect（  admin.aspx）; 
} 
 Response.Redirect（  user.aspx）; 
 
} 
} 

解决方案

它只是通过纠正以下语法来实现 -



SqlCommand com = new SqlCommand（select reg from reg where [user] = @ user and [password] = @ pass，con）;



因为'user'也是sql server中用户的名字，所以当我们想在像这里作为列的其他地方使用它时，我们必须将它用作[user]。

While fetching a record in asp.net from sql server it always return null..here's code- Even if record is available in database, object oid will have null at run time. Please help. thanks.

protected void btnLogin_Click(object sender, EventArgs e)
{
    string cs = ConfigurationManager.ConnectionStrings["DBMS"].ConnectionString;
    SqlConnection con = new SqlConnection(cs);
    SqlCommand com = new SqlCommand("select id from reg where user=@user and password=@pass", con);
    com.Parameters.AddWithValue("@user", txUName.Text);
    com.Parameters.AddWithValue("@pass", txPass.Text);
    con.Open();
    var oid = com.ExecuteScalar();
    con.Close();

    if (oid == null)
    {
        lblEr.Visible = true;
    }
    else
    {
        Session.Add("id", oid.ToString());
        Session.Add("user", txUName.Text);

        com = new SqlCommand("select type from dbo.reg where user=@u", con);
        com.Parameters.AddWithValue("@u", txUName.Text);
        con.Open();
        var otype = com.ExecuteScalar();
        con.Close();

        var vtype = "admin";
        if (vtype == otype.ToString())
        {
            Session.Add("admin", otype.ToString());
            Response.Redirect("admin.aspx");
        }
        Response.Redirect("user.aspx");

    }
}

解决方案

It worked just by correcting following syntax-

SqlCommand com = new SqlCommand("select id from reg where [user]=@user and [password]=@pass", con);

Since 'user' is also name of a user in sql server, so when we want to use it at another place like here as column then we have to use it as [user].

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