512 lines
18 KiB
ReStructuredText
512 lines
18 KiB
ReStructuredText
The QueryBuilder
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================
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A ``QueryBuilder`` provides an API that is designed for
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conditionally constructing a DQL query in several steps.
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It provides a set of classes and methods that is able to
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programmatically build queries, and also provides a fluent API.
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This means that you can change between one methodology to the other
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as you want, and also pick one if you prefer.
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Constructing a new QueryBuilder object
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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The same way you build a normal Query, you build a ``QueryBuilder``
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object, just providing the correct method name. Here is an example
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how to build a ``QueryBuilder`` object:
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.. code-block:: php
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<?php
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// $em instanceof EntityManager
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// example1: creating a QueryBuilder instance
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$qb = $em->createQueryBuilder();
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Once you have created an instance of QueryBuilder, it provides a
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set of useful informative functions that you can use. One good
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example is to inspect what type of object the ``QueryBuilder`` is.
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.. code-block:: php
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<?php
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// $qb instanceof QueryBuilder
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// example2: retrieving type of QueryBuilder
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echo $qb->getType(); // Prints: 0
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There're currently 3 possible return values for ``getType()``:
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- ``QueryBuilder::SELECT``, which returns value 0
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- ``QueryBuilder::DELETE``, returning value 1
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- ``QueryBuilder::UPDATE``, which returns value 2
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It is possible to retrieve the associated ``EntityManager`` of the
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current ``QueryBuilder``, its DQL and also a ``Query`` object when
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you finish building your DQL.
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.. code-block:: php
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<?php
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// $qb instanceof QueryBuilder
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// example3: retrieve the associated EntityManager
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$em = $qb->getEntityManager();
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// example4: retrieve the DQL string of what was defined in QueryBuilder
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$dql = $qb->getDql();
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// example5: retrieve the associated Query object with the processed DQL
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$q = $qb->getQuery();
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Internally, ``QueryBuilder`` works with a DQL cache to increase
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performance. Any changes that may affect the generated DQL actually
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modifies the state of ``QueryBuilder`` to a stage we call
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STATE\_DIRTY. One ``QueryBuilder`` can be in two different states:
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- ``QueryBuilder::STATE_CLEAN``, which means DQL haven't been
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altered since last retrieval or nothing were added since its
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instantiation
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- ``QueryBuilder::STATE_DIRTY``, means DQL query must (and will)
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be processed on next retrieval
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Working with QueryBuilder
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~~~~~~~~~~~~~~~~~~~~~~~~~
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All helper methods in ``QueryBuilder`` actually rely on a single
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one: ``add()``. This method is responsible of building every piece
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of DQL. It takes 3 parameters: ``$dqlPartName``, ``$dqlPart`` and
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``$append`` (default=false)
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- ``$dqlPartName``: Where the ``$dqlPart`` should be placed.
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Possible values: select, from, where, groupBy, having, orderBy
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- ``$dqlPart``: What should be placed in ``$dqlPartName``. Accepts
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a string or any instance of ``Doctrine\ORM\Query\Expr\*``
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- ``$append``: Optional flag (default=false) if the ``$dqlPart``
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should override all previously defined items in ``$dqlPartName`` or
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not
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-
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.. code-block:: php
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<?php
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// $qb instanceof QueryBuilder
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// example6: how to define: "SELECT u FROM User u WHERE u.id = ? ORDER BY u.name ASC" using QueryBuilder string support
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$qb->add('select', 'u')
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->add('from', 'User u')
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->add('where', 'u.id = ?1')
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->add('orderBy', 'u.name ASC');
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Binding parameters to your query
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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Doctrine supports dynamic binding of parameters to your query,
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similar to preparing queries. You can use both strings and numbers
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as placeholders, although both have a slightly different syntax.
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Additionally, you must make your choice: Mixing both styles is not
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allowed. Binding parameters can simply be achieved as follows:
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.. code-block:: php
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<?php
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// $qb instanceof QueryBuilder
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// example6: how to define: "SELECT u FROM User u WHERE u.id = ? ORDER BY u.name ASC" using QueryBuilder string support
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$qb->add('select', 'u')
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->add('from', 'User u')
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->add('where', 'u.id = ?1')
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->add('orderBy', 'u.name ASC');
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->setParameter(1, 100); // Sets ?1 to 100, and thus we will fetch a user with u.id = 100
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You are not forced to enumerate your placeholders as the
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alternative syntax is available:
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.. code-block:: php
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<?php
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// $qb instanceof QueryBuilder
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// example6: how to define: "SELECT u FROM User u WHERE u.id = ? ORDER BY u.name ASC" using QueryBuilder string support
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$qb->add('select', 'u')
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->add('from', 'User u')
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->add('where', 'u.id = :identifier')
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->add('orderBy', 'u.name ASC');
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->setParameter('identifier', 100); // Sets :identifier to 100, and thus we will fetch a user with u.id = 100
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Note that numeric placeholders start with a ? followed by a number
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while the named placeholders start with a : followed by a string.
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If you've got several parameters to bind to your query, you can
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also use setParameters() instead of setParameter() with the
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following syntax:
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.. code-block:: php
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<?php
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// $qb instanceof QueryBuilder
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// Query here...
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$qb->setParameters(array(1 => 'value for ?1', 2 => 'value for ?2'));
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Getting already bound parameters is easy - simply use the above
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mentioned syntax with "getParameter()" or "getParameters()":
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.. code-block:: php
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<?php
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// $qb instanceof QueryBuilder
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// See example above
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$params = qb->getParameters(array(1, 2));
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// Equivalent to
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$param = array($qb->getParameter(1), $qb->getParameter(2));
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Note: If you try to get a parameter that was not bound yet,
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getParameter() simply returns NULL.
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Limiting the Result
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^^^^^^^^^^^^^^^^^^^
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To limit a result the query builder has some methods in common with
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the Query object which can be retrieved from ``EntityManager#createQuery()``.
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.. code-block:: php
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<?php
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// $qb instanceof QueryBuilder
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$offset = (int)$_GET['offset'];
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$limit = (int)$_GET['limit'];
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$qb->add('select', 'u')
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->add('from', 'User u')
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->add('orderBy', 'u.name ASC')
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->setFirstResult( $offset )
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->setMaxResults( $limit );
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Executing a Query
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^^^^^^^^^^^^^^^^^
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The QueryBuilder is a builder object only, it has no means of actually
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executing the Query. Additionally a set of parameters such as query hints
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cannot be set on the QueryBuilder itself. This is why you always have to convert
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a querybuilder instance into a Query object:
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.. code-block:: php
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<?php
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// $qb instanceof QueryBuilder
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$query = $qb->getQuery();
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// Set additional Query options
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$query->setQueryHint('foo', 'bar');
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$query->useResultCache('my_cache_id');
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// Execute Query
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$result = $query->getResult();
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$single = $query->getSingleResult();
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$array = $query->getArrayResult();
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$scalar = $query->getScalarResult();
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$singleScalar = $query->getSingleScalarResult();
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Expr\* classes
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^^^^^^^^^^^^^^
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When you call ``add()`` with string, it internally evaluates to an
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instance of ``Doctrine\ORM\Query\Expr\Expr\*`` class. Here is the
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same query of example 6 written using
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``Doctrine\ORM\Query\Expr\Expr\*`` classes:
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.. code-block:: php
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<?php
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// $qb instanceof QueryBuilder
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// example7: how to define: "SELECT u FROM User u WHERE u.id = ? ORDER BY u.name ASC" using QueryBuilder using Expr\* instances
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$qb->add('select', new Expr\Select(array('u')))
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->add('from', new Expr\From('User', 'u'))
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->add('where', new Expr\Comparison('u.id', '=', '?1'))
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->add('orderBy', new Expr\OrderBy('u.name', 'ASC'));
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Of course this is the hardest way to build a DQL query in Doctrine.
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To simplify some of these efforts, we introduce what we call as
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``Expr`` helper class.
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The Expr class
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^^^^^^^^^^^^^^
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To workaround most of the issues that ``add()`` method may cause,
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Doctrine created a class that can be considered as a helper for
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building queries. This class is called ``Expr``, which provides a
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set of useful static methods to help building queries:
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.. code-block:: php
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<?php
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// $qb instanceof QueryBuilder
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// example8: QueryBuilder port of: "SELECT u FROM User u WHERE u.id = ? OR u.nickname LIKE ? ORDER BY u.surname DESC" using Expr class
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$qb->add('select', $qb->expr()->select('u'))
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->add('from', $qb->expr()->from('User', 'u'))
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->add('where', $qb->expr()->orx(
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$qb->expr()->eq('u.id', '?1'),
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$qb->expr()->like('u.nickname', '?2')
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))
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->add('orderBy', $qb->expr()->orderBy('u.surname', 'ASC'));
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Although it still sounds complex, the ability to programmatically
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create conditions are the main feature of ``Expr``. Here it is a
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complete list of supported helper methods available:
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.. code-block:: php
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<?php
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class Expr
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{
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/** Conditional objects **/
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// Example - $qb->expr()->andx($cond1 [, $condN])->add(...)->...
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public function andx($x = null); // Returns Expr\Andx instance
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// Example - $qb->expr()->orx($cond1 [, $condN])->add(...)->...
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public function orx($x = null); // Returns Expr\Orx instance
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/** Comparison objects **/
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// Example - $qb->expr()->eq('u.id', '?1') => u.id = ?1
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public function eq($x, $y); // Returns Expr\Comparison instance
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// Example - $qb->expr()->neq('u.id', '?1') => u.id <> ?1
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public function neq($x, $y); // Returns Expr\Comparison instance
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// Example - $qb->expr()->lt('u.id', '?1') => u.id < ?1
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public function lt($x, $y); // Returns Expr\Comparison instance
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// Example - $qb->expr()->lte('u.id', '?1') => u.id <= ?1
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public function lte($x, $y); // Returns Expr\Comparison instance
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// Example - $qb->expr()->gt('u.id', '?1') => u.id > ?1
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public function gt($x, $y); // Returns Expr\Comparison instance
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// Example - $qb->expr()->gte('u.id', '?1') => u.id >= ?1
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public function gte($x, $y); // Returns Expr\Comparison instance
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/** Arithmetic objects **/
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// Example - $qb->expr()->prod('u.id', '2') => u.id * 2
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public function prod($x, $y); // Returns Expr\Math instance
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// Example - $qb->expr()->diff('u.id', '2') => u.id - 2
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public function diff($x, $y); // Returns Expr\Math instance
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// Example - $qb->expr()->sum('u.id', '2') => u.id + 2
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public function sum($x, $y); // Returns Expr\Math instance
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// Example - $qb->expr()->quot('u.id', '2') => u.id / 2
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public function quot($x, $y); // Returns Expr\Math instance
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/** Pseudo-function objects **/
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// Example - $qb->expr()->exists($qb2->getDql())
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public function exists($subquery); // Returns Expr\Func instance
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// Example - $qb->expr()->all($qb2->getDql())
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public function all($subquery); // Returns Expr\Func instance
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// Example - $qb->expr()->some($qb2->getDql())
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public function some($subquery); // Returns Expr\Func instance
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// Example - $qb->expr()->any($qb2->getDql())
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public function any($subquery); // Returns Expr\Func instance
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// Example - $qb->expr()->not($qb->expr()->eq('u.id', '?1'))
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public function not($restriction); // Returns Expr\Func instance
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// Example - $qb->expr()->in('u.id', array(1, 2, 3))
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// Make sure that you do NOT use something similar to $qb->expr()->in('value', array('stringvalue')) as this will cause Doctrine to throw an Exception.
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// Instead, use $qb->expr()->in('value', array('?1')) and bind your parameter to ?1 (see section above)
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public function in($x, $y); // Returns Expr\Func instance
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// Example - $qb->expr()->notIn('u.id', '2')
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public function notIn($x, $y); // Returns Expr\Func instance
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// Example - $qb->expr()->like('u.firstname', $qb->expr()->literal('Gui%'))
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public function like($x, $y); // Returns Expr\Comparison instance
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// Example - $qb->expr()->between('u.id', '1', '10')
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public function between($val, $x, $y); // Returns Expr\Func
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/** Function objects **/
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// Example - $qb->expr()->trim('u.firstname')
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public function trim($x); // Returns Expr\Func
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// Example - $qb->expr()->concat('u.firstname', $qb->expr()->concat(' ', 'u.lastname'))
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public function concat($x, $y); // Returns Expr\Func
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// Example - $qb->expr()->substr('u.firstname', 0, 1)
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public function substr($x, $from, $len); // Returns Expr\Func
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// Example - $qb->expr()->lower('u.firstname')
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public function lower($x); // Returns Expr\Func
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// Example - $qb->expr()->upper('u.firstname')
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public function upper($x); // Returns Expr\Func
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// Example - $qb->expr()->length('u.firstname')
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public function length($x); // Returns Expr\Func
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// Example - $qb->expr()->avg('u.age')
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public function avg($x); // Returns Expr\Func
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// Example - $qb->expr()->max('u.age')
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public function max($x); // Returns Expr\Func
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// Example - $qb->expr()->min('u.age')
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public function min($x); // Returns Expr\Func
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// Example - $qb->expr()->abs('u.currentBalance')
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public function abs($x); // Returns Expr\Func
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// Example - $qb->expr()->sqrt('u.currentBalance')
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public function sqrt($x); // Returns Expr\Func
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// Example - $qb->expr()->count('u.firstname')
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public function count($x); // Returns Expr\Func
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// Example - $qb->expr()->countDistinct('u.surname')
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public function countDistinct($x); // Returns Expr\Func
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}
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Helper methods
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^^^^^^^^^^^^^^
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Until now we have described the lowest level (thought of as the
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hardcore method) of creating queries. It may be useful to work at
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this level for optimization purposes, but most of the time it is
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preferred to work at a higher level of abstraction. To simplify
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even more the way you build a query in Doctrine, we can take
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advantage of what we call Helper methods. For all base code, there
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is a set of useful methods to simplify a programmer's life. To
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illustrate how to work with them, here is the same example 6
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re-written using ``QueryBuilder`` helper methods:
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.. code-block:: php
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<?php
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// $qb instanceof QueryBuilder
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// example9: how to define: "SELECT u FROM User u WHERE u.id = ?1 ORDER BY u.name ASC" using QueryBuilder helper methods
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$qb->select('u')
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->from('User', 'u')
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->where('u.id = ?1')
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->orderBy('u.name ASC');
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``QueryBuilder`` helper methods are considered the standard way to
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build DQL queries. Although it is supported, it should be avoided
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to use string based queries and greatly encouraged to use
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``$qb->expr()->*`` methods. Here is a converted example 8 to
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suggested standard way to build queries:
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.. code-block:: php
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<?php
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// $qb instanceof QueryBuilder
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// example8: QueryBuilder port of: "SELECT u FROM User u WHERE u.id = ?1 OR u.nickname LIKE ?2 ORDER BY u.surname DESC" using QueryBuilder helper methods
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$qb->select(array('u')) // string 'u' is converted to array internally
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->from('User', 'u')
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->where($qb->expr()->orx(
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$qb->expr()->eq('u.id', '?1'),
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$qb->expr()->like('u.nickname', '?2')
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))
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->orderBy('u.surname', 'ASC'));
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Here is a complete list of helper methods available in
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``QueryBuilder``:
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.. code-block:: php
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<?php
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class QueryBuilder
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{
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// Example - $qb->select('u')
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// Example - $qb->select(array('u', 'p'))
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// Example - $qb->select($qb->expr()->select('u', 'p'))
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public function select($select = null);
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// Example - $qb->delete('User', 'u')
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public function delete($delete = null, $alias = null);
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// Example - $qb->update('Group', 'g')
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public function update($update = null, $alias = null);
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// Example - $qb->set('u.firstName', $qb->expr()->literal('Arnold'))
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// Example - $qb->set('u.numChilds', 'u.numChilds + ?1')
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// Example - $qb->set('u.numChilds', $qb->expr()->sum('u.numChilds', '?1'))
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public function set($key, $value);
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// Example - $qb->from('Phonenumber', 'p')
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public function from($from, $alias = null);
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// Example - $qb->innerJoin('u.Group', 'g', Expr\Join::ON, $qb->expr()->and($qb->expr()->eq('u.group_id', 'g.id'), 'g.name = ?1'))
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// Example - $qb->innerJoin('u.Group', 'g', 'ON', 'u.group_id = g.id AND g.name = ?1')
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public function innerJoin($join, $alias = null, $conditionType = null, $condition = null);
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// Example - $qb->leftJoin('u.Phonenumbers', 'p', Expr\Join::WITH, $qb->expr()->eq('p.area_code', 55))
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// Example - $qb->leftJoin('u.Phonenumbers', 'p', 'WITH', 'p.area_code = 55')
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public function leftJoin($join, $alias = null, $conditionType = null, $condition = null);
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// NOTE: ->where() overrides all previously set conditions
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//
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// Example - $qb->where('u.firstName = ?1', $qb->expr()->eq('u.surname', '?2'))
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// Example - $qb->where($qb->expr()->andx($qb->expr()->eq('u.firstName', '?1'), $qb->expr()->eq('u.surname', '?2')))
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// Example - $qb->where('u.firstName = ?1 AND u.surname = ?2')
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public function where($where);
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// Example - $qb->andWhere($qb->expr()->orx($qb->expr()->lte('u.age', 40), 'u.numChild = 0'))
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public function andWhere($where);
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// Example - $qb->orWhere($qb->expr()->between('u.id', 1, 10));
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public function orWhere($where);
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// NOTE: -> groupBy() overrides all previously set grouping conditions
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//
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// Example - $qb->groupBy('u.id')
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public function groupBy($groupBy);
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// Example - $qb->addGroupBy('g.name')
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public function addGroupBy($groupBy);
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// NOTE: -> having() overrides all previously set having conditions
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//
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// Example - $qb->having('u.salary >= ?1')
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// Example - $qb->having($qb->expr()->gte('u.salary', '?1'))
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public function having($having);
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// Example - $qb->andHaving($qb->expr()->gt($qb->expr()->count('u.numChild'), 0))
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public function andHaving($having);
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// Example - $qb->orHaving($qb->expr()->lte('g.managerLevel', '100'))
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public function orHaving($having);
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// NOTE: -> orderBy() overrides all previously set ordering conditions
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//
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// Example - $qb->orderBy('u.surname', 'DESC')
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public function orderBy($sort, $order = null);
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// Example - $qb->addOrderBy('u.firstName')
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public function addOrderBy($sort, $order = null); // Default $order = 'ASC'
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}
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