class Select in Zircon Profile 8

PostgreSQL implementation of \Drupal\Core\Database\Query\Select.

Hierarchy

• class \Drupal\Core\Database\Query\Query implements PlaceholderInterface
  • class \Drupal\Core\Database\Query\Select implements SelectInterface uses QueryConditionTrait
    • class \Drupal\Core\Database\Driver\pgsql\Select

Related topics

Database abstraction layer

Allow the use of different database servers using the same code base.

5 string references to 'Select'

Connection::select in core/lib/Drupal/Core/Database/Connection.php

Prepares and returns a SELECT query object.

ConnectionTest::providerGetDriverClass in core/tests/Drupal/Tests/Core/Database/ConnectionTest.php

Dataprovider for testGetDriverClass().

FilterPluginBase::buildExposedFiltersGroupForm in core/modules/views/src/Plugin/views/filter/FilterPluginBase.php

Build the form to let users create the group of exposed filters. This form is displayed when users click on button 'Build group'

FormTestValidateRequiredForm::buildForm in core/modules/system/tests/modules/form_test/src/Form/FormTestValidateRequiredForm.php

Form constructor.

form_test.routing.yml in core/modules/system/tests/modules/form_test/form_test.routing.yml

core/modules/system/tests/modules/form_test/form_test.routing.yml

File

core/lib/Drupal/Core/Database/Driver/pgsql/Select.php, line 20

Contains \Drupal\Core\Database\Driver\pgsql\Select.

Namespace

Drupal\Core\Database\Driver\pgsql

class Select extends QuerySelect {
  public function orderRandom() {
    $alias = $this
      ->addExpression('RANDOM()', 'random_field');
    $this
      ->orderBy($alias);
    return $this;
  }

  /**
   * Overrides SelectQuery::orderBy().
   *
   * PostgreSQL adheres strictly to the SQL-92 standard and requires that when
   * using DISTINCT or GROUP BY conditions, fields and expressions that are
   * ordered on also need to be selected. This is a best effort implementation
   * to handle the cases that can be automated by adding the field if it is not
   * yet selected.
   *
   * @code
   *   $query = db_select('example', 'e');
   *   $query->join('example_revision', 'er', 'e.vid = er.vid');
   *   $query
   *     ->distinct()
   *     ->fields('e')
   *     ->orderBy('timestamp');
   * @endcode
   *
   * In this query, it is not possible (without relying on the schema) to know
   * whether timestamp belongs to example_revision and needs to be added or
   * belongs to node and is already selected. Queries like this will need to be
   * corrected in the original query by adding an explicit call to
   * SelectQuery::addField() or SelectQuery::fields().
   *
   * Since this has a small performance impact, both by the additional
   * processing in this function and in the database that needs to return the
   * additional fields, this is done as an override instead of implementing it
   * directly in SelectQuery::orderBy().
   */
  public function orderBy($field, $direction = 'ASC') {

    // Only allow ASC and DESC, default to ASC.
    // Emulate MySQL default behavior to sort NULL values first for ascending,
    // and last for descending.
    // @see http://www.postgresql.org/docs/9.3/static/queries-order.html
    $direction = strtoupper($direction) == 'DESC' ? 'DESC NULLS LAST' : 'ASC NULLS FIRST';
    $this->order[$field] = $direction;
    if ($this
      ->hasTag('entity_query')) {
      return $this;
    }

    // If there is a table alias specified, split it up.
    if (strpos($field, '.') !== FALSE) {
      list($table, $table_field) = explode('.', $field);
    }

    // Figure out if the field has already been added.
    foreach ($this->fields as $existing_field) {
      if (!empty($table)) {

        // If table alias is given, check if field and table exists.
        if ($existing_field['table'] == $table && $existing_field['field'] == $table_field) {
          return $this;
        }
      }
      else {

        // If there is no table, simply check if the field exists as a field or
        // an aliased field.
        if ($existing_field['alias'] == $field) {
          return $this;
        }
      }
    }

    // Also check expression aliases.
    foreach ($this->expressions as $expression) {
      if ($expression['alias'] == $this->connection
        ->escapeAlias($field)) {
        return $this;
      }
    }

    // If a table loads all fields, it can not be added again. It would
    // result in an ambiguous alias error because that field would be loaded
    // twice: Once through table_alias.* and once directly. If the field
    // actually belongs to a different table, it must be added manually.
    foreach ($this->tables as $table) {
      if (!empty($table['all_fields'])) {
        return $this;
      }
    }

    // If $field contains an characters which are not allowed in a field name
    // it is considered an expression, these can't be handled automatically
    // either.
    if ($this->connection
      ->escapeField($field) != $field) {
      return $this;
    }

    // This is a case that can be handled automatically, add the field.
    $this
      ->addField(NULL, $field);
    return $this;
  }

  /**
   * {@inheritdoc}
   */
  public function addExpression($expression, $alias = NULL, $arguments = array()) {
    if (empty($alias)) {
      $alias = 'expression';
    }

    // This implements counting in the same manner as the parent method.
    $alias_candidate = $alias;
    $count = 2;
    while (!empty($this->expressions[$alias_candidate])) {
      $alias_candidate = $alias . '_' . $count++;
    }
    $alias = $alias_candidate;
    $this->expressions[$alias] = array(
      'expression' => $expression,
      'alias' => $this->connection
        ->escapeAlias($alias_candidate),
      'arguments' => $arguments,
    );
    return $alias;
  }

  /**
   * {@inheritdoc}
   */
  public function execute() {
    $this->connection
      ->addSavepoint();
    try {
      $result = parent::execute();
    } catch (\Exception $e) {
      $this->connection
        ->rollbackSavepoint();
      throw $e;
    }
    $this->connection
      ->releaseSavepoint();
    return $result;
  }

}

Members

Name	Modifiers	Type	Description	Overrides
Query::$comments	protected	property	An array of comments that can be prepended to a query.
Query::$connection	protected	property	The connection object on which to run this query.
Query::$connectionKey	protected	property	The key of the connection object.
Query::$connectionTarget	protected	property	The target of the connection object.
Query::$nextPlaceholder	protected	property	The placeholder counter.
Query::$queryOptions	protected	property	The query options to pass on to the connection object.
Query::$uniqueIdentifier	protected	property	A unique identifier for this query object.
Query::comment	public	function	Adds a comment to the query.
Query::getComments	public	function	Returns a reference to the comments array for the query.
Query::nextPlaceholder	public	function	Gets the next placeholder value for this query object. Overrides PlaceholderInterface::nextPlaceholder
Query::uniqueIdentifier	public	function	Returns a unique identifier for this object. Overrides PlaceholderInterface::uniqueIdentifier
Query::__sleep	public	function	Implements the magic __sleep function to disconnect from the database.
Query::__wakeup	public	function	Implements the magic __wakeup function to reconnect to the database.
QueryConditionTrait::$condition	protected	property	The condition object for this query.
QueryConditionTrait::andConditionGroup	public	function
QueryConditionTrait::condition	public	function
QueryConditionTrait::conditionGroupFactory	public	function
QueryConditionTrait::conditions	public	function
QueryConditionTrait::exists	public	function
QueryConditionTrait::isNotNull	public	function
QueryConditionTrait::isNull	public	function
QueryConditionTrait::notExists	public	function
QueryConditionTrait::orConditionGroup	public	function
QueryConditionTrait::where	public	function
Select::$distinct	protected	property	Whether or not this query should be DISTINCT
Select::$expressions	protected	property	The expressions to SELECT as virtual fields.
Select::$fields	protected	property	The fields to SELECT.
Select::$forUpdate	protected	property	The FOR UPDATE status	1
Select::$group	protected	property	The fields by which to group.
Select::$having	protected	property	The conditional object for the HAVING clause.
Select::$order	protected	property	The fields by which to order this query.
Select::$prepared	protected	property	Indicates if preExecute() has already been called.
Select::$range	protected	property	The range limiters for this query.
Select::$tables	protected	property	The tables against which to JOIN.
Select::$union	protected	property	An array whose elements specify a query to UNION, and the UNION type. The 'type' key may be '', 'ALL', or 'DISTINCT' to represent a 'UNION', 'UNION ALL', or 'UNION DISTINCT'…
Select::addExpression	public	function	Adds an expression to the list of "fields" to be SELECTed. Overrides Select::addExpression
Select::addField	public	function	Adds a field to the list to be SELECTed. Overrides SelectInterface::addField
Select::addJoin	public	function	Join against another table in the database. Overrides SelectInterface::addJoin
Select::addMetaData	public	function	Adds additional metadata to the query. Overrides AlterableInterface::addMetaData
Select::addTag	public	function	Adds a tag to a query. Overrides AlterableInterface::addTag
Select::arguments	public	function	Gets a complete list of all values to insert into the prepared statement. Overrides QueryConditionTrait::arguments
Select::compile	public	function	Compiles the saved conditions for later retrieval. Overrides QueryConditionTrait::compile
Select::compiled	public	function	Check whether a condition has been previously compiled. Overrides QueryConditionTrait::compiled
Select::countQuery	public	function	Get the equivalent COUNT query of this query as a new query object. Overrides SelectInterface::countQuery
Select::distinct	public	function	Sets this query to be DISTINCT. Overrides SelectInterface::distinct
Select::escapeField	public	function	Escapes a field name string. Overrides SelectInterface::escapeField
Select::escapeLike	public	function	Escapes characters that work as wildcard characters in a LIKE pattern. Overrides SelectInterface::escapeLike
Select::execute	public	function	Runs the query against the database. Overrides Select::execute
Select::extend	public	function	Enhance this object by wrapping it in an extender object. Overrides ExtendableInterface::extend
Select::fields	public	function	Add multiple fields from the same table to be SELECTed. Overrides SelectInterface::fields
Select::forUpdate	public	function	Add FOR UPDATE to the query. Overrides SelectInterface::forUpdate	1
Select::getArguments	public	function	Compiles and returns an associative array of the arguments for this prepared statement. Overrides SelectInterface::getArguments
Select::getExpressions	public	function	Returns a reference to the expressions array for this query. Overrides SelectInterface::getExpressions
Select::getFields	public	function	Returns a reference to the fields array for this query. Overrides SelectInterface::getFields
Select::getGroupBy	public	function	Returns a reference to the group-by array for this query. Overrides SelectInterface::getGroupBy
Select::getMetaData	public	function	Retrieves a given piece of metadata. Overrides AlterableInterface::getMetaData
Select::getOrderBy	public	function	Returns a reference to the order by array for this query. Overrides SelectInterface::getOrderBy
Select::getTables	public	function	Returns a reference to the tables array for this query. Overrides SelectInterface::getTables
Select::getUnion	public	function	Returns a reference to the union queries for this query. This include queries for UNION, UNION ALL, and UNION DISTINCT. Overrides SelectInterface::getUnion
Select::groupBy	public	function	Groups the result set by the specified field. Overrides SelectInterface::groupBy
Select::hasAllTags	public	function	Determines if a given query has all specified tags. Overrides AlterableInterface::hasAllTags
Select::hasAnyTag	public	function	Determines if a given query has any specified tag. Overrides AlterableInterface::hasAnyTag
Select::hasTag	public	function	Determines if a given query has a given tag. Overrides AlterableInterface::hasTag
Select::having	public	function	Adds an arbitrary HAVING clause to the query. Overrides SelectInterface::having
Select::havingArguments	public	function	Gets a list of all values to insert into the HAVING clause. Overrides SelectInterface::havingArguments
Select::havingCompile	public	function	Compiles the HAVING clause for later retrieval. Overrides SelectInterface::havingCompile
Select::havingCondition	public	function	Helper function to build most common HAVING conditional clauses. Overrides SelectInterface::havingCondition
Select::havingConditions	public	function	Gets a list of all conditions in the HAVING clause. Overrides SelectInterface::havingConditions
Select::havingExists	public	function	Sets a HAVING condition that the specified subquery returns values. Overrides SelectInterface::havingExists
Select::havingIsNotNull	public	function	Sets a condition in the HAVING clause that the specified field be NOT NULL. Overrides SelectInterface::havingIsNotNull
Select::havingIsNull	public	function	Sets a condition in the HAVING clause that the specified field be NULL. Overrides SelectInterface::havingIsNull
Select::havingNotExists	public	function	Sets a HAVING condition that the specified subquery returns no values. Overrides SelectInterface::havingNotExists
Select::innerJoin	public	function	Inner Join against another table in the database. Overrides SelectInterface::innerJoin
Select::isPrepared	public	function	Indicates if preExecute() has already been called on that object. Overrides SelectInterface::isPrepared
Select::join	public	function	Default Join against another table in the database. Overrides SelectInterface::join
Select::leftJoin	public	function	Left Outer Join against another table in the database. Overrides SelectInterface::leftJoin
Select::orderBy	public	function	Overrides SelectQuery::orderBy(). Overrides Select::orderBy
Select::orderRandom	public	function	Orders the result set by a random value. Overrides Select::orderRandom
Select::preExecute	public	function	Generic preparation and validation for a SELECT query. Overrides SelectInterface::preExecute
Select::prepareCountQuery	protected	function	Prepares a count query from the current query object.
Select::range	public	function	Restricts a query to a given range in the result set. Overrides SelectInterface::range
Select::rightJoin	public	function	Right Outer Join against another table in the database. Overrides SelectInterface::rightJoin
Select::union	public	function	Add another Select query to UNION to this one. Overrides SelectInterface::union
Select::__clone	public	function	Implements the magic __clone function. Overrides Query::__clone
Select::__construct	public	function	Constructs a Select object. Overrides Query::__construct
Select::__toString	public	function	Implements PHP magic __toString method to convert the query to a string. Overrides Query::__toString