PHP（Phalcon框架）和MySQL：模型关系与JOIN

Question

For example there are 3 tables:

• products
• product_images
• product_specs

And there are one-to-one relationships in models of this 3 tables.

By showing 50 products on page - it get more +2 extra queries inside cycle, so in total there are 150 rows and cool object:

$products = Products::find();
foreach ($products as $product)
{
    $product->name;
    $product->images->filename;
    $product->specs->volume;
}

Or just create custom method in Products Model and JOIN all necessary tables:

$products = Products::getComplete();
foreach ($products as $product)
{
    $product->name;
    $product->imageFile;
    $product->specVolume;
}

So, i'm wondering: is 1st practice is useful and don't make high load on MySQL daemon or slowing drastically php script execution time?

Answer 1

Answer to your first question: that practice could be useful, but would depend on your exact implementation.

But, you are right. Using built-in one-to-one relationship will query the related model each time it's referenced which is intensive. So:

$products->images

is a new query for each record.

Fortunately, there is a better, more efficient way that achieves the same result - PHQL.

Since a one-to-one is basically a joined table that is called up via a second query (when it really doesn't need to), you could accomplish the same thing by doing something like:

$products =
    (new \Phalcon\Mvc\Model)
        ->getModelsManager()
        ->executeQuery(
            "SELECT   products.*, product_images.*, product_specs.* ".
            "FROM     Products    AS products ".
            "JOIN     ProductImages AS product_images ".
            "ON       products.id = product_images.product_id ".
            "JOIN     ProductSpecs AS product_specs ".
            "ON       products.id = product_specs.product_id");

which will only do a single query and give you the same information you wanted before.

This is just one of those times where you have to identify expensive queries and choose an alternate method.