User-1939834628 postedI need to use a DropDownList as a control to provide parameters to my query.
<asp:ControlParameter
Direction="Input"
DbType="String"
ControlID="_ddlMonth"
ConvertEmptyStringToNull="true"
PropertyName="SelectedValue"
DefaultValue=""
Name="month" />
Such DropDownList is defined like this:
<asp:DropDownList
ClientIDMode="Static"
ID="_ddlMese"
runat="server"
EnableViewState="true" >
<asp:ListItem Value="" Text="ANY" Selected ="True" />
<asp:ListItem Value="1" Text="January" />
<asp:ListItem Value="2" Text="February" />
<asp:ListItem Value="3" Text="March" />
<asp:ListItem Value="4" Text="April" />
<asp:ListItem Value="5" Text="May" />
<asp:ListItem Value="6" Text="June" />
<asp:ListItem Value="7" Text="July" />
<asp:ListItem Value="8" Text="August" />
<asp:ListItem Value="9" Text="Septemeber" />
<asp:ListItem Value="10" Text="October" />
<asp:ListItem Value="11" Text="November" />
<asp:ListItem Value="12" Text="December" />
</asp:DropDownList>
The value ANY should be used to bypass month check in my query as described below.
My SelectCommand includes an AND section in WHERE clause:
AND ((@month IS NULL) OR (table.month = @month))
I thought ANY value (empty string) should be converted to NULL at the time it becomes a parameter value.
The query works fine if I choose a real month value (from DDL) but if I select ANY, even if I specified ConvertEmptyStringToNull="true" option in ControlParameter, @month parameter never get NULL and the query probably ends up checking somehting like this:
'' IS NULL
that's never true and then returns no records.
There's a way to fix this?
