Native SQL
==========
A ``NativeQuery`` lets you execute native SELECT SQL statements, mapping the results
according to your specifications. Such a specification that
describes how an SQL result set is mapped to a Doctrine result is
represented by a ``ResultSetMapping``. It describes how each column
of the database result should be mapped by Doctrine in terms of the
object graph. This allows you to map arbitrary SQL code to objects,
such as highly vendor-optimized SQL or stored-procedures.
Because writing ``ResultSetMapping`` is not so simple, there is a convenience
wrapper around it called a ``ResultSetMappingBuilder``. The last section
of this chapter describes its usage.
.. note::
If you want to execute DELETE, UPDATE or INSERT statements
the Native SQL API cannot be used and will probably throw errors.
Use ``EntityManager#getConnection()`` to access the native database
connection and call the ``executeUpdate()`` method for these
queries.
The NativeQuery class
---------------------
To create a ``NativeQuery`` you use the method
``EntityManager#createNativeQuery($sql, $resultSetMapping)``. As
you can see in the signature of this method, it expects 2
ingredients: The SQL you want to execute and the
``ResultSetMapping`` that describes how the results will be
mapped.
Once you obtained an instance of a ``NativeQuery``, you can bind
parameters to it and finally execute it.
The ResultSetMapping
--------------------
Understanding the ``ResultSetMapping`` is the key to using a
``NativeQuery``. A Doctrine result can contain the following
components:
- Entity results. These represent root result elements.
- Joined entity results. These represent joined entities in
associations of root entity results.
- Field results. These represent a column in the result set that
maps to a field of an entity. A field result always belongs to an
entity result or joined entity result.
- Scalar results. These represent scalar values in the result set
that will appear in each result row. Adding scalar results to a
ResultSetMapping can also cause the overall result to become
**mixed** (see DQL - Doctrine Query Language) if the same
ResultSetMapping also contains entity results.
- Meta results. These represent columns that contain
meta-information, such as foreign keys and discriminator columns.
When querying for objects (``getResult()``), all meta columns of
root entities or joined entities must be present in the SQL query
and mapped accordingly using ``ResultSetMapping#addMetaResult``.
.. note::
It might not surprise you that Doctrine uses
``ResultSetMapping`` internally when you create DQL queries. As
the query gets parsed and transformed to SQL, Doctrine fills a
``ResultSetMapping`` that describes how the results should be
processed by the hydration routines.
We will now look at each of the result types that can appear in a
ResultSetMapping in detail.
Entity results
~~~~~~~~~~~~~~
An entity result describes an entity type that appears as a root
element in the transformed result. You add an entity result through
``ResultSetMapping#addEntityResult()``. Let's take a look at the
method signature in detail:
.. code-block:: php
addEntityResult('User', 'u');
$rsm->addFieldResult('u', 'id', 'id');
$rsm->addFieldResult('u', 'name', 'name');
$query = $this->_em->createNativeQuery('SELECT id, name FROM users WHERE name = ?', $rsm);
$query->setParameter(1, 'romanb');
$users = $query->getResult();
The result would look like this:
.. code-block:: php
array(
[0] => User (Object)
)
Note that this would be a partial object if the entity has more
fields than just id and name. In the example above the column and
field names are identical but that is not necessary, of course.
Also note that the query string passed to createNativeQuery is
**real native SQL**. Doctrine does not touch this SQL in any way.
In the previous basic example, a User had no relations and the
table the class is mapped to owns no foreign keys. The next example
assumes User has a unidirectional or bidirectional one-to-one
association to a CmsAddress, where the User is the owning side and
thus owns the foreign key.
.. code-block:: php
addEntityResult('User', 'u');
$rsm->addFieldResult('u', 'id', 'id');
$rsm->addFieldResult('u', 'name', 'name');
$rsm->addMetaResult('u', 'address_id', 'address_id');
$query = $this->_em->createNativeQuery('SELECT id, name, address_id FROM users WHERE name = ?', $rsm);
$query->setParameter(1, 'romanb');
$users = $query->getResult();
Foreign keys are used by Doctrine for lazy-loading purposes when
querying for objects. In the previous example, each user object in
the result will have a proxy (a "ghost") in place of the address
that contains the address\_id. When the ghost proxy is accessed, it
loads itself based on this key.
Consequently, associations that are *fetch-joined* do not require
the foreign keys to be present in the SQL result set, only
associations that are lazy.
.. code-block:: php
addEntityResult('User', 'u');
$rsm->addFieldResult('u', 'id', 'id');
$rsm->addFieldResult('u', 'name', 'name');
$rsm->addJoinedEntityResult('Address' , 'a', 'u', 'address');
$rsm->addFieldResult('a', 'address_id', 'id');
$rsm->addFieldResult('a', 'street', 'street');
$rsm->addFieldResult('a', 'city', 'city');
$sql = 'SELECT u.id, u.name, a.id AS address_id, a.street, a.city FROM users u ' .
'INNER JOIN address a ON u.address_id = a.id WHERE u.name = ?';
$query = $this->_em->createNativeQuery($sql, $rsm);
$query->setParameter(1, 'romanb');
$users = $query->getResult();
In this case the nested entity ``Address`` is registered with the
``ResultSetMapping#addJoinedEntityResult`` method, which notifies
Doctrine that this entity is not hydrated at the root level, but as
a joined entity somewhere inside the object graph. In this case we
specify the alias 'u' as third parameter and ``address`` as fourth
parameter, which means the ``Address`` is hydrated into the
``User::$address`` property.
If a fetched entity is part of a mapped hierarchy that requires a
discriminator column, this column must be present in the result set
as a meta column so that Doctrine can create the appropriate
concrete type. This is shown in the following example where we
assume that there are one or more subclasses that extend User and
either Class Table Inheritance or Single Table Inheritance is used
to map the hierarchy (both use a discriminator column).
.. code-block:: php
addEntityResult('User', 'u');
$rsm->addFieldResult('u', 'id', 'id');
$rsm->addFieldResult('u', 'name', 'name');
$rsm->addMetaResult('u', 'discr', 'discr'); // discriminator column
$rsm->setDiscriminatorColumn('u', 'discr');
$query = $this->_em->createNativeQuery('SELECT id, name, discr FROM users WHERE name = ?', $rsm);
$query->setParameter(1, 'romanb');
$users = $query->getResult();
Note that in the case of Class Table Inheritance, an example as
above would result in partial objects if any objects in the result
are actually a subtype of User. When using DQL, Doctrine
automatically includes the necessary joins for this mapping
strategy but with native SQL it is your responsibility.
ResultSetMappingBuilder
-----------------------
There are some downsides with Native SQL queries. The primary one is that you have to adjust all result set mapping
definitions if names of columns change. In DQL this is detected dynamically when the Query is regenerated with
the current metadata.
To avoid this hassle you can use the ``ResultSetMappingBuilder`` class. It allows to add all columns of an entity
to a result set mapping. To avoid clashes you can optionally rename specific columns when you are doing the same
in your sQL statement:
.. code-block:: php
addRootEntityFromClassMetadata('MyProject\User', 'u');
$rsm->addJoinedEntityFromClassMetadata('MyProject\Address', 'a', 'u', 'address', array('id' => 'address_id'));
For entities with more columns the builder is very convenient to use. It extends the ``ResultSetMapping`` class
and as such has all the functionality of it as well. Currently the ``ResultSetMappingBuilder`` does not support
entities with inheritance.
Named Native Query
------------------
You can also map a native query using a named native query mapping.
To achieve that, you must describe the SQL resultset structure
using named native query (and sql resultset mappings if is a several resultset mappings).
Like named query, a named native query can be defined at class level or in a XML or YAML file.
A resultSetMapping parameter is defined in @NamedNativeQuery,
it represents the name of a defined @SqlResultSetMapping.
.. configuration-block::
.. code-block:: php
SELECT u.id AS u_id, u.name AS u_name, u.status AS u_status, a.id AS a_id, a.zip AS a_zip, a.country AS a_country, COUNT(p.phonenumber) AS numphones FROM users u INNER JOIN addresses a ON u.id = a.user_id INNER JOIN phonenumbers p ON u.id = p.user_id GROUP BY u.id, u.name, u.status, u.username, a.id, a.zip, a.country ORDER BY u.username
.. code-block:: yaml
MyProject\Model\User:
type: entity
namedNativeQueries:
fetchMultipleJoinsEntityResults:
name: fetchMultipleJoinsEntityResults
resultSetMapping: mappingMultipleJoinsEntityResults
query: SELECT u.id AS u_id, u.name AS u_name, u.status AS u_status, a.id AS a_id, a.zip AS a_zip, a.country AS a_country, COUNT(p.phonenumber) AS numphones FROM users u INNER JOIN addresses a ON u.id = a.user_id INNER JOIN phonenumbers p ON u.id = p.user_id GROUP BY u.id, u.name, u.status, u.username, a.id, a.zip, a.country ORDER BY u.username
sqlResultSetMappings:
mappingMultipleJoinsEntityResults:
name: mappingMultipleJoinsEntityResults
columnResult:
0:
name: numphones
entityResult:
0:
entityClass: __CLASS__
fieldResult:
0:
name: id
column: u_id
1:
name: name
column: u_name
2:
name: status
column: u_status
1:
entityClass: Address
fieldResult:
0:
name: id
column: a_id
1:
name: zip
column: a_zip
2:
name: country
column: a_country
Things to note:
- The resultset mapping declares the entities retrieved by this native query.
- Each field of the entity is bound to an SQL alias (or column name).
- All fields of the entity including the ones of subclasses
and the foreign key columns of related entities have to be present in the SQL query.
- Field definitions are optional provided that they map to the same
column name as the one declared on the class property.
- ``__CLASS__`` is a alias for the mapped class
In the above example,
the ``fetchJoinedAddress`` named query use the joinMapping result set mapping.
This mapping returns 2 entities, User and Address, each property is declared and associated to a column name,
actually the column name retrieved by the query.
Let's now see an implicit declaration of the property / column.
.. configuration-block::
.. code-block:: php
SELECT * FROM addresses
.. code-block:: yaml
MyProject\Model\Address:
type: entity
namedNativeQueries:
findAll:
resultSetMapping: mappingFindAll
query: SELECT * FROM addresses
sqlResultSetMappings:
mappingFindAll:
name: mappingFindAll
entityResult:
address:
entityClass: Address
In this example, we only describe the entity member of the result set mapping.
The property / column mappings is done using the entity mapping values.
In this case the model property is bound to the model_txt column.
If the association to a related entity involve a composite primary key,
a @FieldResult element should be used for each foreign key column.
The @FieldResult name is composed of the property name for the relationship,
followed by a dot ("."), followed by the name or the field or property of the primary key.
.. configuration-block::
.. code-block:: php
SELECT u.id, u.name, u.status, a.id AS a_id, a.country AS a_country, a.zip AS a_zip, a.city AS a_city FROM users u INNER JOIN addresses a ON u.id = a.user_id WHERE u.username = ?
.. code-block:: yaml
MyProject\Model\User:
type: entity
namedNativeQueries:
fetchJoinedAddress:
name: fetchJoinedAddress
resultSetMapping: mappingJoinedAddress
query: SELECT u.id, u.name, u.status, a.id AS a_id, a.country AS a_country, a.zip AS a_zip, a.city AS a_city FROM users u INNER JOIN addresses a ON u.id = a.user_id WHERE u.username = ?
sqlResultSetMappings:
mappingJoinedAddress:
entityResult:
0:
entityClass: __CLASS__
fieldResult:
0:
name: id
1:
name: name
2:
name: status
3:
name: address.id
column: a_id
4:
name: address.zip
column: a_zip
5:
name: address.city
column: a_city
6:
name: address.country
column: a_country
If you retrieve a single entity and if you use the default mapping,
you can use the resultClass attribute instead of resultSetMapping:
.. configuration-block::
.. code-block:: php
SELECT * FROM addresses WHERE id = ?
.. code-block:: yaml
MyProject\Model\Address:
type: entity
namedNativeQueries:
findAll:
name: findAll
resultClass: Address
query: SELECT * FROM addresses
In some of your native queries, you'll have to return scalar values,
for example when building report queries.
You can map them in the @SqlResultsetMapping through @ColumnResult.
You actually can even mix, entities and scalar returns in the same native query (this is probably not that common though).
.. configuration-block::
.. code-block:: php
SELECT COUNT(*) AS count FROM addresses
.. code-block:: yaml
MyProject\Model\Address:
type: entity
namedNativeQueries:
count:
name: count
resultSetMapping: mappingCount
query: SELECT COUNT(*) AS count FROM addresses
sqlResultSetMappings:
mappingCount:
name: mappingCount
columnResult:
count:
name: count