c#asp.net下拉列表选择值

我对我的代码感到困惑，不知道如何实现我想要的。我有两个sql表，一个表有OfficeID和匹配的OfficeName，另一个表包含user。我有一个页面，允许一个人编辑有关此人的信息。加载页面时，应该从下拉列表中选择其信息正在编辑的人员的当前OfficeName。因此我有了这个：

对于我的C#和SQL知识水平来说，这可能是非常低效和令人困惑的，但我决心学习如何做到这一点。我目前拥有的是在创建下拉列表之前，我得到用户Id，然后从数据库中选择他相应的officeID，然后在创建下拉列表时，我检查OfficeID是否与另一个表中的OfficeID相对应。如果找到匹配项，则会将其设置为下拉列表的选定值。

我走对了吗？在转换loginID之前，我需要弄清楚如何比较SESLoginID=loginID。有什么帮助吗？

using System;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;
using System.Collections;
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 Functions;
using HelloApp;
public partial class UserUpdate : Page
{
    private Int32 loginID = 0;
    protected void Page_Load(object sender, EventArgs e)
    {
        loginID = Convert.ToInt32(Request.QueryString["SESLoginID"]);
       if (!Page.IsPostBack)
        {
            BindBusinessUnitDDL();
        }
    }
    protected void BindBusinessUnitDDL()
    {
        SqlConnection conn;
        string sql;
        SqlCommand cmd;
        int error;
        conn = Database.DBConnect(out error);
        sql = String.Format("SELECT OfficeID FROM SESLogin WHERE SESLoginID = loginID");
        cmd = new SqlCommand(sql, conn);
        SqlDataReader rdrr = cmd.ExecuteReader();
        ListItem office = new ListItem();
        office.Value = Convert.ToString(rdrr.GetInt32(0));
        Database.DBClose(conn);   
        sql = String.Format(
            "SELECT OfficeID, OfficeName FROM Office");
        cmd = new SqlCommand(sql, conn);
        SqlDataReader rdr = cmd.ExecuteReader();
        DropDownList ddlBusinessUnit = (DropDownList)(this.LoginFormView.FindControl("ddlBusinessUnit"));
        while (rdr.Read())
        {
            ListItem myItem = new ListItem();
            myItem.Value = Convert.ToString(rdr.GetInt32(0));
            myItem.Text = rdr.GetString(1);
            ddlBusinessUnit.Items.Add(myItem);
            if(office.Value == myItem.Value){
                ddlBusinessUnit.SelectedValue = myItem.Text;
            }
        }
        Database.DBClose(conn);        
        ddlBusinessUnit.DataBind();
        PageUser myUser = new PageUser();
    }

存在使用登录ID返回OfficeName的过程的代码的另一个版本。Doesnt work要么给出错误：系统数据SqlClient。SqlException：转换nvarchar值"SELECT"时转换失败[办公室名称]FROM sesuser。SES登录INNER JOIN sesuser。办公室ON sesuser。办公室OfficeID=sesuser。SES登录。OfficeIDWHERE SESLoginID LIKE"287"到数据类型int.

public partial class UserUpdate : Page
{
    private Int32 loginID = 0;
    private String loginIDE = "";
    protected void Page_Load(object sender, EventArgs e)
    {
        loginIDE = Request.QueryString["SESLoginID"];
        loginID = Convert.ToInt32(Request.QueryString["SESLoginID"]);
       if (!Page.IsPostBack)
        {
            BindBusinessUnitDDL();
        }
    }
    protected void BindBusinessUnitDDL()
        {
            SqlConnection connec = null;
            SqlCommand cmd = null;
            string sqls = "";
            int errNum = 0;
            connec = Database.DBConnect(out errNum);
            if (errNum != 0)
                throw new Exception("Database Connection Error.");
            sqls = "Login_GetOffice";
            cmd = new SqlCommand(sqls, connec);
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.Parameters.AddWithValue("@userID", loginIDE);
            string office = (string)cmd.ExecuteScalar();
        SqlConnection conn;
        string sql;
        int error;
        conn = Database.DBConnect(out error);
        sql = String.Format(
            "SELECT OfficeID, OfficeName FROM Office");
        cmd = new SqlCommand(sql, conn);
        SqlDataReader rdr = cmd.ExecuteReader();
        DropDownList ddlBusinessUnit = (DropDownList)(this.LoginFormView.FindControl("ddlBusinessUnit"));
        while (rdr.Read())
        {
            ListItem myItem = new ListItem();
            myItem.Value = Convert.ToString(rdr.GetInt32(0));
            myItem.Text = rdr.GetString(1);
            ddlBusinessUnit.Items.Add(myItem);
            if(office == myItem.Text){
                myItem.Selected = true;
            }
        }
        Database.DBClose(conn);        
        ddlBusinessUnit.DataBind();
        PageUser myUser = new PageUser();
    }

ddlBusinessUnit.DataBind();?