Question

I’ve two tables, location and forecast. I’d like to query the database to find all locations that match forecast parameters for each day.

e.g. London has forecast entries for the days 2011-07-13, 2011-07-14, 2011-07-15, and 2011-07-16. I’d like London to be returned if on 2011-07-14 AND 2011-07-15 the temperature is not higher than 40 and not lower than 13.

I’ve managed to work this out in MySQL (I think):

SELECT f1.day, f1.temperature_high, f1.temperature_low, f2.day, f2.temperature_high, f2.temperature_low, l.name 
FROM location l
INNER JOIN forecast f1 ON 
  f1.location_id = l.id AND 
  f1.day = '2011-07-14' AND 
  f1.temperature_high <= '40' AND 
  f1.temperature_low >= '13'
INNER JOIN forecast f2 ON 
  f2.location_id = l.id AND 
  f2.day = '2011-07-15' AND 
  f2.temperature_high <= '40' AND 
  f2.temperature_low >= '13';

I attempted to translate this into Doctrine, but I’m getting memory exhausted errors. My Doctrine query:

$this->results = Doctrine_Query::create()->select('l.name')->from('Location l');


foreach ($values['day'] as $i => $day) {
  $this->results->innerJoin('l.Forecasts f'.$i.' ON 
    f'.$i.'.condition_id IN (' . implode(',', $values['condition']) . ') AND 
    f'.$i.'.temperature_high <= ' .$values['temperature_max'] . ' AND 
    f'.$i.'.temperature_low >= ' . $values['temperature_min']);
}
$this->results->execute();

What is the correct & most efficient way of running this query? I’m pretty sure I’m doing something fundamentally wrong.

Many thanks in advance
Pete

Answer 1

I think it would be easier to use $query->addWhere('EXISTS (...)') with an inner select statement for each condition.

$this->results = Doctrine_Query::create()->select('name')->from('location');

foreach ($values['day'] as $i => $day) {
    $this->results->addWhere('EXISTS (
        SELECT NULL
        FROM forecast
        WHERE location_id = location.id
        AND condition_id IN (' . implode(',', $values['condition']) . ')
        AND temperature_high <= ' . $values['temperature_max'] . '
        AND temperature_low >= ' . $values['temperature_min'] . '
    )');
}
$this->results->execute();