You do this:

function setup()
{
    $this-src('db')->query("{your query to get the parameters}")
    ->saveTo($params_src)
    ->pipe($this->dataStore('params'));

    $params_src->start();
    //Now you can get the params from dataStore
    $params = $this->dataStore("params")->data();
    //The $params is an array of associate array containing your parameters
    //Now you can continue to get your real query
     
    $this->src('db')->query("{Your real query}")
    ->params(array(
        ":myparam"=>$params[0]["name_of_param"]
    ))
    ->pipe($this->dataStore('results'));
}

Hope that helps.

Hi, I have tested this case and it works well. The issue could be:

1. {your query to get the parameters} is not correct
2. The query return empty data.

Great!