如何从SQL表获取数据到下拉数据值字段 [英] How can I get data from SQL table to dropdown datavalue field

问题描述

SL	COURSE_CAT	          COURSECAT_ID
1	HEALTH & SAFETY	              1
2	FOOD & HYGIENE	              2
3	FIRST AID	                 3
4	FIRE SAFETY	                 4

SL	COURSE	         COURSE_ID	 COURSE_CODE
1	BB-GENTS	    1	           BBNTS
2	BB-LADIES	    1	           BBLDS
3	PIC-2 BARBER	    1	           PBRB
4	HSO-LABOUR ACC	    1	           HLBR
5	BASIC FOOD	    2	           BSFD
6	PIC-2 FOOD	    2	           PIFD
7	FIRST AID WORK	3	FIAD

我尝试过：

What I have tried:

<asp:DropDownList ID="ddcoursecat" runat="server" Height="20px" Width="168px" OnSelectedIndexChanged="ddcoursecat_SelectedIndexChanged" AutoPostBack="True">
                                                  </asp:DropDownList>

------------------------------- -------------------------------------------------- -----

--------------------------------------------------------------------------------------

<asp:DropDownList ID="ddcourse" runat="server" Height="20px" Width="168px" AutoPostBack="True">
                                                    </asp:DropDownList>

------------------------ -------------------------------------------------- ------------

--------------------------------------------------------------------------------------

I have two dropdown control (Course_cat, course)
Course dd is getting populated from course table using Course_cat ID.
my intention is if a Course is selected its datavalue field should bind corresponding Course code from course_code column.
please help me to solve this.

------------------------ -------------------------------------------------- ----------

------------------------------------------------------------------------------------

protected void ddcoursecat_SelectedIndexChanged(object sender, EventArgs e)
       {
               ddshift.Items.Insert(0, new ListItem("---SELECT---", "0"));
             //  ddcourse.Items.Insert(0, new ListItem("---SELECT---", "0"));
              // ddcourse.SelectedIndex = (0);
               try
               {
                   string CS = ConfigurationManager.ConnectionStrings["erpconnect"].ConnectionString;

                   using (SqlConnection con = new SqlConnection(CS))
                   {
                       SqlCommand cmd = new SqlCommand("SELECT  COURSE,COURSE_CODE from tbl_course WHERE COURSECAT_ID=" + ddcoursecat.SelectedValue +"", con);
                       {
                           if (ddcoursecat.SelectedIndex == 0)
                           {
                               ddcourse.Items.Insert(0, new ListItem("---SELECT---", "0"));
                          }
                           else
                           {

                               ddcourse.Items.Insert(0, new ListItem("---SELECT---", "0"));
                               con.Open();
                               ddcourse.DataSource = cmd.ExecuteReader();
                               ddcourse.DataTextField = "COURSE";
                               ddcourse.DataValueField = "COURSE_CODE";
                               ddcourse.DataBind();
                           }

                       }
                   }
               }
               catch
               {


               }

               finally
               {
                   this.Dispose();
               }

推荐答案

您没有提供有关您的问题的足够信息，因此我只建议您按照此链接的说明：使用ASP.NET C＃从数据库表填充ASP.Net下拉列表 [ ^ ]

You did not provide enough information about your issue, so i can only recommend you to follow the instruction from this link: Fill ASP.Net Dropdown List From Database Table Using ASP.NET C#[^]

你问的是这个和过度而无视问题。为什么会出错？您的代码正在执行插入操作。它需要读取数据库并填充列表。



为什么在2019年使用ASP.NET？

You are asking this over and over and ignoring questions. Why is going wrong? Your code is doing an insert. It needs to read the database and populate a list.

Why are you using ASP.NET in 2019?

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