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a check box change dropdown1 default value if a check box has been

Question

User1298215938 posted

<form id="form1" runat="server">  
    <table style="width: 100%; height: 86px;">  
        <tr>  
            <td class="style1">  
                <asp:Label ID="Label1" runat="server" Text="Choose Your Country :"></asp:Label>  
            </td>  
            <td>  
                <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True"   
                    DataTextField="country_name" DataValueField="country_id" AppendDataBoundItems="true"   
                    onselectedindexchanged="DropDownList1_SelectedIndexChanged">  
                    <asp:ListItem Value="0">--Select Country--</asp:ListItem>  
                </asp:DropDownList>  
            </td>  
            <td>  
                 </td>  
        </tr>  
        <tr>  
            <td class="style1">  
                <asp:Label ID="Label2" runat="server" Text="Choose Your State :"></asp:Label>  
            </td>  
            <td>  
                <asp:DropDownList ID="DropDownList2" runat="server" AppendDataBoundItems="true" DataTextField="state_name"   
                    DataValueField="state_id" AutoPostBack="True"   
                    onselectedindexchanged="DropDownList2_SelectedIndexChanged">  
                    <asp:ListItem Value="0">-- Select State--</asp:ListItem>  
                </asp:DropDownList>  
            </td>  
            <td>  
                 </td>  
        </tr>  
        <tr>  
            <td class="style1">  
                <asp:Label ID="Label3" runat="server" Text="Choose Your City :"></asp:Label>  
            </td>  
            <td>  
                <asp:DropDownList ID="DropDownList3" runat="server" AppendDataBoundItems="true" DataTextField="city_name"   
                    DataValueField="city_id">  
                    <asp:ListItem Value="0">-- Select City--</asp:ListItem>  
                </asp:DropDownList>  
            </td>  
            <td>  
                 </td>  
        </tr>  
    </table>  
    <div>  
   </div>  
</form>

protected void Page_Load(object sender, EventArgs e)  
{  
    if (!Page.IsPostBack)  
    {  
        SqlConnection con = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Database.mdf;Integrated Security=True;User Instance=True");  
        SqlCommand cmd = new SqlCommand("select * from tbl_country", con);  
        SqlDataAdapter sda = new SqlDataAdapter(cmd);  
        DataTable dt = new DataTable();  
        sda.Fill(dt);  
        DropDownList1.DataSource = dt;  
        DropDownList1.DataBind();  
          
    }  
  
}  
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)  
{  
    DropDownList2.Items.Clear();  
    DropDownList2.Items.Add("Select State");  
  
    SqlConnection con = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Database.mdf;Integrated Security=True;User Instance=True");  
    SqlCommand cmd = new SqlCommand("select * from tbl_state where country_id=" + DropDownList1.SelectedItem.Value, con);  
    SqlDataAdapter sda = new SqlDataAdapter(cmd);  
    DataTable dt = new DataTable();  
    sda.Fill(dt);  
    DropDownList2.DataSource= dt;  
    DropDownList2.DataBind();  
}  
protected void DropDownList2_SelectedIndexChanged(object sender, EventArgs e)  
{  
    DropDownList3.Items.Clear();  
    DropDownList3.Items.Add("Select State");  
  
    SqlConnection con = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Database.mdf;Integrated Security=True;User Instance=True");  
    SqlCommand cmd = new SqlCommand("select * from tbl_city where state_id=" + DropDownList2.SelectedItem.Value, con);  
    SqlDataAdapter sda = new SqlDataAdapter(cmd);  
    DataTable dt = new DataTable();  
    sda.Fill(dt);  
  
    DropDownList3.DataSource = dt;  
    DropDownList3.DataBind();  
  
}

if Checkbox checked how can i disable a item from dropdownlist one even tho its connected to SQL server?

Thursday, October 1, 2020 8:00 PM

Answers

User1535942433 posted

Hi MOHIIMRAN,

Accroding to your description and codes,could you tell us where is your checkbox?

As far as I think,when you check your checkbox,you could select again and not equal the checkbox's text.And then ,you could rebind the dropdown again.

More details,you could refer to below codes:

 <table style="width: 100%; height: 86px;">
            <tr>
                <td>
                    <asp:CheckBox ID="CheckBox1" runat="server" OnCheckedChanged="CheckBox1_CheckedChanged" Text="China" AutoPostBack="true" /></td>
                <td></td>
                <td></td>
            </tr>
            <tr>
                <td class="style1">
                    <asp:Label ID="Label1" runat="server" Text="Choose Your Country :"></asp:Label>
                </td>
                <td>
                    <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True"
                        DataTextField="CountryName" DataValueField="CountryID" AppendDataBoundItems="true" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged">
                        <asp:ListItem Value="0">--Select Country--</asp:ListItem>
                    </asp:DropDownList>
                </td>
                <td></td>
            </tr>
            <tr>
                <td class="style1">
                    <asp:Label ID="Label2" runat="server" Text="Choose Your State :"></asp:Label>
                </td>
                <td>
                    <asp:DropDownList ID="DropDownList2" runat="server" AppendDataBoundItems="true" DataTextField="StateName"
                        DataValueField="State_Id" AutoPostBack="True" OnSelectedIndexChanged="DropDownList2_SelectedIndexChanged">
                        <asp:ListItem Value="0">-- Select State--</asp:ListItem>
                    </asp:DropDownList>
                </td>
                <td></td>
            </tr>
            <tr>
                <td class="style1">
                    <asp:Label ID="Label3" runat="server" Text="Choose Your City :"></asp:Label>
                </td>
                <td>
                    <asp:DropDownList ID="DropDownList3" runat="server" AppendDataBoundItems="true" DataTextField="CityName"
                        DataValueField="CityID">
                        <asp:ListItem Value="0">-- Select City--</asp:ListItem>
                    </asp:DropDownList>
                </td>
                <td></td>
            </tr>
            <tr>
                <td></td>
                <td><asp:Button ID="Enter" runat="server" Text="Enter" /></td>
                <td></td>
            </tr>
        </table>

Code-behind:

 protected void Page_Load(object sender, EventArgs e)
        {
            if (!Page.IsPostBack)
            {
                string str;
                str = System.Configuration.ConfigurationManager.ConnectionStrings["aspnet-TestApplicationWithDatabase-20190820030542"].ConnectionString;
                SqlConnection conn = new SqlConnection(str);
                SqlCommand cmd = new SqlCommand("select * from Country", conn);
                SqlDataAdapter sda = new SqlDataAdapter(cmd);
                DataTable dt = new DataTable();
                sda.Fill(dt);
                DropDownList1.DataSource = dt;
                DropDownList1.DataBind();
                conn.Close();
                Enter.Visible = false;
            }
        }

        protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
        {
            DropDownList2.Items.Clear();
            DropDownList2.Items.Add("Select State");
            string str;
            str = System.Configuration.ConfigurationManager.ConnectionStrings["aspnet-TestApplicationWithDatabase-20190820030542"].ConnectionString;
            SqlConnection conn = new SqlConnection(str);
            SqlCommand cmd = new SqlCommand("select * from State where country_id=" + DropDownList1.SelectedItem.Value, conn);
            SqlDataAdapter sda = new SqlDataAdapter(cmd);
            DataTable dt = new DataTable();
            sda.Fill(dt);
            DropDownList2.DataSource = dt;
            DropDownList2.DataBind();
        }

        protected void DropDownList2_SelectedIndexChanged(object sender, EventArgs e)
        {
            DropDownList3.Items.Clear();
            DropDownList3.Items.Add("Select State");
            string str;
            str = System.Configuration.ConfigurationManager.ConnectionStrings["aspnet-TestApplicationWithDatabase-20190820030542"].ConnectionString;
            SqlConnection conn = new SqlConnection(str);
            SqlCommand cmd = new SqlCommand("select * from City where state_id=" + DropDownList2.SelectedItem.Value, conn);
            SqlDataAdapter sda = new SqlDataAdapter(cmd);
            DataTable dt = new DataTable();
            sda.Fill(dt);

            DropDownList3.DataSource = dt;
            DropDownList3.DataBind();
            Enter.Visible = true;
        }

        protected void CheckBox1_CheckedChanged(object sender, EventArgs e)
        {
            if (CheckBox1.Checked == true)
            {
                DropDownList1.Items.Clear();
                DropDownList1.Items.Add("Select Country");
                string str;
                str = System.Configuration.ConfigurationManager.ConnectionStrings["aspnet-TestApplicationWithDatabase-20190820030542"].ConnectionString;
                SqlConnection conn = new SqlConnection(str);
                string sql= "select * from Country where CountryName <>'" + CheckBox1.Text +"'";
                SqlCommand cmd = new SqlCommand(sql , conn);
                SqlDataAdapter sda = new SqlDataAdapter(cmd);
                DataTable dt = new DataTable();
                sda.Fill(dt);
                DropDownList1.DataSource = dt;
                DropDownList1.DataBind();
            }
        }

Result:

Best regards,

Yijing Sun

Marked as answer by Anonymous Thursday, October 7, 2021 12:00 AM

Friday, October 2, 2020 3:31 AM

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a check box change dropdown1 default value if a check box has been

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