asp:QueryStringParameter and empty query string parameter

asp.net .net sql-server sqldatasource querystringparameter

SqlDataSource won't fire if any of it's parameters are null, unless you specify otherwise:

<asp:SqlDataSource CancelSelectOnNullParameter="False" />

It might also be necessary to add a null default value to your querystring parameter:

<asp:QueryStringParameter Name="client" QueryStringField="client" DefaultValue="" ConvertEmptyStringToNull="True" />

asp.net .net sql-server sqldatasource querystringparameter

You need to define a Default value to the parameter for those situations, for example:

<asp:QueryStringParameter Name="client" QueryStringField="client" DefaultValue="0"/>

and then in the SP you need verify if the client is 0, return all the clients, otherwise the specific one.

CodeHunter