Binding ASP.Net GridView before Item is Selected in DropDownList in ASP.Net

HI

HI

i have 2 page

1-index.aspx

2-state .aspx

when users click on menubar in index.aspx they go to state.aspx 

in State.aspx is gridview with 6 Dropdownlist that occording to their selected item from DDL they can see result in gridview

now my problem is :

when i click item from menubar in index.aspx when it go to state.aspx it doesn't show any thing in gridview. 

i want at first  when users go to state.aspx page they can see all data in gridview after that they select item from DDL and see result according to their selected item

SP

ALTER procedure [dbo].[ViewEstate1]

@Type nvarchar(20)
,@Transfer nvarchar(20)
,@measure varchar(20)
,@Zone nvarchar(50)
,@City nvarchar(20)
,@District nvarchar(30)

as

begin

select id,Transfer,Type,Measure,price,zone,date,District,substring([address],0,18)+'...' as address 
from Estate_p
where (Type=@Type or @Type='همه') and (Transfer=@Transfer or @Transfer='all') and  (Measure=@measure or @measure='all') and (City=@City or @City='all') and (zone=@Zone or zone='all') and (District=@District or @District='all')
order by date
end

behind code

    private void BindData()
    {
            SqlCommand cmd = new SqlCommand("ViewEstate1", _cn);
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.Parameters.AddWithValue("@Type", ddltype.SelectedItem.Text);
            cmd.Parameters.AddWithValue("@Transfer", ddlTran.SelectedItem.Text.Trim());
            cmd.Parameters.AddWithValue("@measure", ddlmeter.SelectedItem.Text.Trim());
            cmd.Parameters.AddWithValue("@City", DDLcity1.SelectedItem.Text.Trim());
            cmd.Parameters.AddWithValue("@Zone", DDLzone1.SelectedItem.Text.Trim());
            cmd.Parameters.AddWithValue("@District", ddldistric1.SelectedItem.Text.Trim());

            GridView2.DataSource = GetData(cmd);
            GridView2.DataBind();
        
    }

Thanks alot