Zend DB and Conditional Case Statements

Question

Hey,

I have a zend app that displays a league table of race results. The basic process is to determine the list of events to be included, and then dynamically add a set of columns to a SQL query. My initial implementation is rather rubbish and i want to refector it. I manually build up a string of SQL and at the very end call db->fetch(). I know - crap code, but i was still learning zend and had a deadline.

public function league()
{
    ...

    $SQL = 'SELECT rr.runner AS runnerid, ru.firstname as firstname, ru.surname as surname, ';

    // get the list of events        
    foreach($events as $eventrow)
    {
        $eventTable = new Model_DbTable_Event();
        $event = $eventTable->find($eventrow->event)->current();
        // generate the conditional column
        $sum = $this->getEventSQL($event,$division->gender);
        // append to the SQL string (nasty) 
        $SQL = $SQL . $sum;
    }

    $SQL = $SQL . 'lrd.racesComplete, lrd.pointsTotal, c.name as company ';
    $SQL = $SQL . 'FROM raceresult rr ';
    $SQL = $SQL . 'JOIN runner ru ON rr.runner = ru.id ';
    $SQL = $SQL . 'LEFT JOIN company c ON c.id = ru.company ';
    $SQL = $SQL . 'JOIN race ra ON rr.race = ra.id ';
    ...
    ...

    $db = Zend_Db_Table::getDefaultAdapter();
    $this->view->leaguetable = $db->fetchAll($SQL);
}

// create the SUM sql statement for a specific event
// SUM(CASE rr.race WHEN 15 THEN rr.points ELSE NULL END) as Result1,
// SUM(CASE rr.race WHEN 16 THEN rr.points ELSE NULL END) as Result2,
function getEventSQL($event,$type)
{
    $eventTable = new Model_DbTable_Event();
    $sum_sql = 'SUM(CASE rr.race ';
    foreach($races as $race)
    {
        $sum_sql = $sum_sql . sprintf('WHEN %d',$race->id) . ' THEN rr.points ';
    }   
    $sum_sql = $sum_sql . sprintf('ELSE NULL END) as \'%s\',',$event->id);
    return $sum_sql;
}

I know i need to use the SQL SELECT/CASE statements.

http://stackoverflow.com/questions/849348/conditional-column-for-query-based-on-other-columns-in-mysql

I want to move this logic to a class that extends Zend_Db_Table_Abstract but i'm still unsure what is the best way to conditionally control the columns that are selected. I know i can add multiple where() clauses, can the column() method be used in this scenario?

class Model_DbTable_League extends Zend_Db_Table_Abstract
{
    protected $_name = 'leaguerunnerdata';
    protected $_primary = 'Id';

    public function leagueTable($min,$max)
    {
        $sql = $this->select()
            ->setIntegrityCheck(false)
            ->from(array('l'=>'league'),array('col','col2','col3'))
            ->where('l.league = ?',1)
            ->where('r.standard > ?',$min)
            ->where('r.standard < ?',$max)
            ->order('l.pointsTotal DESC');
        return $this->fetchAll($sql);
    }

....

Any ideas/suggestions?

Answer 1

The perfecto answerino

$select = $this->select()->setIntegrityCheck(false)

$select->from(array('l' => 'league'), array('leagueId'=> 'id', 'name','location','competitionName','eventManager','owner' )  )
                ->join(array('r' => 'whateverRTableIs'),
                         'r.id = l.id',
                             array())
                ->where('l.league = ?',1)
                ->where('r.standard > ?',$min)
                ->where('r.standard < ?',$max)
                ->order('l.pointsTotal DESC');
            return $this->fetchAll($select);

Answer 2

I figured out that i could use the 'columns()' method to dynamically add extra fields to my query, and use the Zend_Db_Expr to correctly format the specific value for the column.

$select = $this->select()
->setIntegrityCheck(false)
->from(array('raceresult'=>'raceresult'),array())
->join(array('runner'=>'runner'),'runner.id=raceresult.runner',array('id','firstname','surname'));
    foreach($races as $taggedrace)
    {
        $select->columns(new Zend_Db_Expr(
            sprintf("SUM(CASE raceresult.race WHEN %d THEN raceresult.points ELSE NULL END) as %s",
                $taggedrace->raceid,$taggedrace->tag)));
    }
$select->join(array('race'=>'race'),'race.id = raceresult.race',array())
->join(array('event'=>'event'),'race.event = event.id',array())
->join(array('leagueevent'=>'leagueevent'),'leagueevent.event = event.id',array())
->join(array('leaguerunnerdata'=>'leaguerunnerdata'),
    'leaguerunnerdata.runner = raceresult.runner AND leaguerunnerdata.league=leagueevent.league',
    array('racesComplete','pointsTotal'))
->joinLeft(array('company'=>'company'), 'company.id = runner.company',array('name'))
->where( sprintf('leaguerunnerdata.standard BETWEEN %d AND %d ',$division->min,$division->max))
->where('runner.gender= ?',$division->gender)
->where('leagueevent.league = ?',$league)
->group(array('raceresult.runner','leaguerunnerdata.racesComplete','leaguerunnerdata.pointsTotal'))
->order(array('leaguerunnerdata.pointsTotal desc'));