c# - 根据查询结果中的记录预选多选列表框中的值

Question

想象一下这张桌子：

MatchID UserID  MatchField        MatchValue
7          5    MatchInterests        3
8          5    MatchInterests        7
9          5    MatchInterests       12
10         5    MatchInterests       20
11         5    MatchInterests       26
12         2    MatchInterests        7
13         2    MatchInterests       26
14         4    MatchInterests       26
15         5    MatchStates          12
16         5    MatchStates          11
17         2    MatchStates           1
18         2    MatchStates          17
19         4    MatchStates          10

我想要做的是在用户 5 的列表框中为字段 MatchInterests 预先选择 MatchValues 值。因此，我想要预选的结果数据集如下所示：

MatchID UserID  MatchField        MatchValue
7          5    MatchInterests        3
8          5    MatchInterests        7
9          5    MatchInterests       12
10         5    MatchInterests       20
11         5    MatchInterests       26

最好的方法是什么？

我试图做的是：

string strSQL2 = "SELECT MatchValue FROM tmpUsermatch WHERE MatchField = 'MatchInterests' AND UserID = '" + (DT2["UserID"].ToString()) + "'";
Interests.SelectionMode = ListSelectionMode.Multiple;
using (var con = new SqlConnection(strCon1))
using (var adapter2 = new SqlDataAdapter(strSQL2, con))
   {
     DataTable dt2 = new DataTable();
     adapter2.Fill(dt2);
     foreach (DataRow row in dt2.Rows)
     {
       Interests.SelectedValue = row["MatchValue"].ToString();
     }
   }

这可行，但只会导致选择数据集的最后一条记录中的值，并且我需要选择每条记录中的值。

按要求：控制名称兴趣的标记。

<tr>
   <td style="width:160px">
      <asp:Label ID="Label26" runat="server" AssociatedControlID="Interests">Interests:</asp:Label>
   </td>
   <td style="width:300px">
      <div id="UCStyle1">
        <asp:ListBox ID="Interests" SelectionMode="Multiple" runat="server">
        </asp:ListBox>
      </div>
   </td>
</tr>

Answer 1

You are effectively overwriting SelectedValue on each iteration of the loop which is why you are only seeing the last one selected.

You need to set the Selected property on the items themselves or use the ListBox.SetSelected() method. There is an example on the method's documentation page.

So, instead of

Interests.SelectedValue = row["MatchValue"].ToString();

you would have

Interests.SetSelected(x, true);

where x is the index of the list item you want to select. You might need to work out the index by e.g. getting the item based on row["MatchValue"] if you don't have the indices available at hand.