ISO/IEC 9075

• SQL-86 (or SQL-87)
• SQL-89
• SQL-92
• SQL:1999
• SQL:2003
• SQL:2006
• SQL:2008
• SQL:2011
• SQL:2016
• SQL:2019

Insert new entity

    $entity = new Foo('value');

    $entityManager->persist($entity);

    $entityManager->flush();
            

DQL or find()

    SELECT e FROM Foo e WHERE e.id = 42
            

    $foo = $entityManager->find(Foo::class, 42);
            

Insert new entity

    $entity = new Foo('value');

    $entityManager->persist($entity);

    $entityManager->flush(); // <-- There's SQL somewhere in there
            

Update entity (default tracking policy)

    $entity = $entityManager
        ->find(Foo::class, 42); // <-- There's SQL somewhere in there

    $entity->setValue('new value');

    $entityManager->flush(); // <-- There's SQL somewhere in there
            

What Unit Of Work does

    $entity = $entityManager->find(Foo::class, 42);
    
    // ... sooo much code
    
    $entity = $entityManager->find(Foo::class, 42); // <-- No SQL query
            

All languages

• de
• en
• it

Clear EntityManager/Unit Of Work

    $entityManager->persist($movie);
    $entityManager->flush();

    $entityManager->clear(); // <-- Clear enities from the EntityManager/Unit Of Work

    $movie = $entityManager->createQuery(
            "SELECT m, l FROM Movie m
            JOIN m.languages l
            WHERE l.iso6391 = 'it' AND f.name = 'The Mutex'"
        )
        ->getResult();

    $movie[0]->getLanguages();
            

Clear

    $entityManager->clear();
    $entityManager->clear(Entity::class); // Deprecated
            

Lazy vs. Eager Loading

    class Foo
    {
        // ...

        /**
         * @var Bar[]
         *
         * Use LAZY or EAGER in fetch
         */
        #[ORM\OneToMany(targetEntity: 'Bar', mappedBy: 'foo', fetch: 'LAZY')]
        private $bars;

        // ...
    }
            

Lazy Loading

  $foos = $entityManager->getRepository(Foo::class)
      ->findAll(); // <-- There's SQL somewhere in there

  foreach ($foos as $foo) {
      foreach ($foo->getBars() as $bar) { // <-- There's SQL somewhere in there
          // do stuff
      }
  }
            

Eager Loading

    $foos = $entityManager->getRepository(Foo::class)
        ->findAll(); // <-- There's SQL somewhere in there

    foreach ($foos as $foo) {
        foreach ($foo->getBars() as $bar) {
            // do stuff
        }
    }
            

Same code, different SQL

  -- findAll() returns 3 Foo entities
  SELECT t0.id AS id_1, t0.name AS name_2 FROM foo t0
  -- Each query is one iteration for getting the Bar relations
  SELECT t0.id AS id_1, t0.name AS name_2, t0.foo_id AS foo_id_3 FROM bar t0 WHERE t0.foo_id = 1
  SELECT t0.id AS id_1, t0.name AS name_2, t0.foo_id AS foo_id_3 FROM bar t0 WHERE t0.foo_id = 2
  SELECT t0.id AS id_1, t0.name AS name_2, t0.foo_id AS foo_id_3 FROM bar t0 WHERE t0.foo_id = 3
            

  -- findAll() returns 3 Foo entities and joins the bar relation
  SELECT t0.id AS id_1, t0.name AS name_2, t3.id AS id_4, t3.name AS name_5, t3.foo_id AS foo_id_6
      FROM foo t0
      LEFT JOIN bar t3 ON t3.foo_id = t0.id
            

Explicit join - One query

SELECT f, b FROM Entity\Foo f JOIN f.bars b
            

SELECT f0_.id AS id_0, f0_.name AS name_1, b1_.id AS id_2, b1_.name AS name_3, b1_.foo_id AS foo_id_4
    FROM foo f0_
    INNER JOIN bar b1_ ON f0_.id = b1_.foo_id
            

    SELECT q FROM Entity\Qux q WHERE q.city = 'Hahnland'
            

Full table scan

Index scan

    select * from qux WHERE city = 'Hahnland';
            

Before

Next release

Equal code, different SQL

    SELECT f FROM Entity\Foo f
            

    SELECT f0_.id AS id_0, f0_.name AS name_1 FROM foo f0_
        WHERE (f0_.deleted = 0);
            

Slow SQL queries

• Need more resources
• May lock rows / Waiting queries

DBAL QueryBuilder

    $queryBuilder->where('f.id = 1')
        ->select('f.name', 'f.id', 'b.name as bname', 'q.stuff')
        ->leftJoin('f', 'bar', 'b', 'b.foo_id = f.id')
        ->from('foo', 'f')
        ->orWhere('f.id = 2')
        ->leftJoin('f', 'qux', 'q', 'q.foo_id = f.id'); // join order?

    if ($yolo) {
        $queryBuilder->andWhere('q.moreStuff = true');
    }
            

Window Function

    SELECT name, department,
        SUM(revenue) OVER (PARTITION BY department ORDER BY name)
        FROM company;
            

Values List

    VALUES ('value1', 42, 1.8), ('value2', 12, 9);
            

Values List in DB Versions

• PostgreSQL: Yes - 8.2 (and earlier)
• MariaDB: Yes - 10.3
• MySQL: 8.0.19 (But with ROW syntax)

JSON

MySQL/MariaDB

    SELECT JSON_OBJECT('a', name, 'b', number) AS jayson FROM foo;
            

PostgreSQL

    SELECT JSON_BUILD_OBJECT('a', name, 'b', number) AS jayson FROM foo;
            

Common Table Expression (CTE)

    WITH bar (col1, col2) AS (SELECT id, content FROM foo)

    SELECT * FROM bar;
            

With Recursive

    WITH RECURSIVE cat AS (
        SELECT * from category WHERE name = 'A'
        UNION ALL
        SELECT cat_recursive.* from category as cat_recursive
            JOIN cat AS parent ON parent.id = cat_recursive.parent_id
    )
    SELECT * FROM cat;
            

With Recursive

This was just the tip of the iceberg

Dev Toolbar

SQL fiddles

• dbfiddle.uk
• sqlfiddle.com

Thank you

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