关于sqldatareader的问题

Question

我要用sqldatareader查找某用户是否存在？如果存在，就在Label上显示除姓名和密码以外的其它信息，如：性别、年龄、住址，要如何操作？请给个例子

Answer 1

SqlConnection conn = new SqlConnection("server=.;database=northwind;uid=sa;pwd=;");
        string sqlStr = "select * from employees where employeeid=@id";
        SqlCommand cmd = new SqlCommand(sqlStr,conn);
        cmd.Parameters.Add("@id",SqlDbType.Int);
        cmd.Parameters["@id"].Value = this.TextBox1.Text;
        conn.Open();
        SqlDataReader dr = cmd.ExecuteReader();
        if (dr.Read())
        {
            this.Label1.Text = dr["firstname"].ToString();
            this.Label2.Text = dr["address"].ToString();
            this.Label3.Text = dr["title"].ToString();
        }
        dr.Close();
        conn.Close();

Answer 2

SqlConnection connect = new SqlConnection("server=(local);database=db;uid=sa;pwd=;");
SqlCommand cmd = new SqlCommand("select * from user_table where userid=@userid and password=@password", connect);
using (SqlDataReader read = cmd.ExecuteReader())
{
    if(read.read())
    {
        //表示输入的用户名密码正确
         this.lblName.Text = read["name"].ToString().Trim();//取姓名，姓名字段是 name,其它的一样
    }
    else
    {
        //表示输入的用户名密码错误
     }
}

Answer 3

不好意思少了两句
cmd.Parameters.AddWithValue("@userid", this.txtUserID.Text.Trim());
cmd.Parameters.AddWithValue("@password", this.txtPwd.Text.Trim());

Answer 4

 SqlConnection con = new SqlConnection(ConfigurationManager.AppSettings["conStr"]);
                con.Open();                string pwd = this.passWord.Text.Trim().Replace("'", "''");
                string sqlstr = "select * from student where student_num=@user and student_pwd=@password";
                SqlCommand cmd = new SqlCommand(sqlstr, con);                cmd.Parameters.Add(new SqlParameter("@user", SqlDbType.VarChar, 50));
                cmd.Parameters["@user"].Value = userName.Text.ToString();                cmd.Parameters.Add(new SqlParameter("@password", SqlDbType.VarChar, 50));
                cmd.Parameters["@password"].Value = System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(pwd, "MD5").ToString();//密码加密
                SqlDataReader dr = cmd.ExecuteReader();
                if (dr.Read())
                {
                    Response.Redirect("student/default.aspx", false);
                    Session["student_num"] = userName.Text.ToString();
                }
                else
                {
                    con.Close();
                    Response.Write("<script>alert('您必须输入有效的用户名和密码！');history.back()</script>");
                    return;                }