数据库中的下拉列表

Question

我看不到我创建的下拉列表（单击此链接获得图像）

这是我在add.aspx.cs中的代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

//ADO.NET
using System.Data;
using System.Data.SqlClient;
using System.IO;

public partial class Admin_Users_Add : System.Web.UI.Page
{
    SqlConnection con = new SqlConnection(kmb.GetConnection());
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            GetCategoryTypes();
        }
    }
    /// <summary>
    /// Allows the user to display list of user types
    /// from the table Types to the dropdownlist control
    /// </summary>
    void GetCategoryTypes()
    {
        con.Open();
        SqlCommand cmd = new SqlCommand();
        cmd.Connection = con;
        cmd.CommandText = "SELECT CatID, Category FROM Categories";
        SqlDataReader dr = cmd.ExecuteReader();
        ddlCategoryTypes.DataSource = dr;
        ddlCategoryTypes.DataTextField = "Category";
        ddlCategoryTypes.DataValueField = "CatID";
        ddlCategoryTypes.DataBind();

        ddlCategoryTypes.Items.Insert(0, new ListItem("Select one...", ""));
        con.Close();
    }
}

在数据库中，我创建了2个表：

类别（CatID [PK]，类别[FK]）

CategoryTypes（类别[PK]，开胃菜，甜品，饮料）

----我想在我的网页的数据库下拉列表中看到“开胃菜，甜点，饮料”

Answer 1

您需要将查询更改为：

        con.Open();
        SqlCommand cmd = new SqlCommand();
        cmd.Connection = con;
        cmd.CommandText = "SELECT CatID, Appetizers +', '+ Desserts +', '+ Beverages as CatDescription FROM Categories Inner Join CategoryTypes ON Categories.Category = CategoryTypes.Category";
        SqlDataReader dr = cmd.ExecuteReader();
        ddlCategoryTypes.DataSource = dr;
        ddlCategoryTypes.DataTextField = "CatDescription";
        ddlCategoryTypes.DataValueField = "CatID";
        ddlCategoryTypes.DataBind();

        ddlCategoryTypes.Items.Insert(0, new ListItem("Select one...", ""));
        con.Close();