//================a.aspx如下:===================//
<asp:CheckBoxList ID="Certification" RepeatDirection="Horizontal" runat="server">
<asp:ListItem Value="ISO-9000" Text="ISO-9000"></asp:ListItem>
<asp:ListItem Value="ISO-9002" Text="ISO-9002"></asp:ListItem>
<asp:ListItem Value="ISO-9003" Text="ISO-9003"></asp:ListItem>
<asp:ListItem Value="ISO-9004" Text="ISO-9004"></asp:ListItem>
<asp:ListItem Value="ISO-14000" Text="ISO-14000"></asp:ListItem>
</asp:CheckBoxList> //================a.aspx.cs的Page_Load如下===================//
string Cert = membershowok["CertificationList"].ToString();
string[] CertID = Cert.Split(' ');
            for (int x = 0; x < CertID.Length-1; x++)
            {
                switch (CertID[x])
                {
                    case "ISO-9000":
                        Certification.Items[0].Selected = true;
                        break;
                    case "ISO-9002":
                        Certification.Items[1].Selected = true;
                        break;
                    case "ISO-9003":
                        Certification.Items[2].Selected = true;
                        break;
                    case "ISO-9004":
                        Certification.Items[3].Selected = true;
                        break;
                    case "ISO-14000":
                        Certification.Items[4].Selected = true;
                        break;
                }
            }
//================a.aspx.cs的Button1_Click如下===================//
string CertificationList="";
        for (int i = 0; i < Certification.Items.Count; i++)//判断有几个选中
        {
            if (Certification.Items[i].Selected == true)
            {
                CertificationList += Certification.Items[i].Value + " ";
            }
        }
如果用户第一次录入没问题,就是修改的时候不知道为什么怎么都取消不了
例如开始选了3个,到后来只能增加,却不能减少选项