select.inc 40.7 KB
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<?php
// $Id$

/**
 * @ingroup database
 * @{
 */

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/**
 * Interface for extendable query objects.
 *
 * "Extenders" follow the "Decorator" OOP design pattern.  That is, they wrap
 * and "decorate" another object.  In our case, they implement the same interface
 * as select queries and wrap a select query, to which they delegate almost all
 * operations.  Subclasses of this class may implement additional methods or
 * override existing methods as appropriate.  Extenders may also wrap other
 * extender objects, allowing for arbitrarily complex "enhanced" queries.
 */
interface QueryExtendableInterface {

  /**
   * Enhance this object by wrapping it in an extender object.
   *
   * @param $extender_name
   *   The base name of the extending class.  The base name will be checked
   *   against the current database connection to allow driver-specific subclasses
   *   as well, using the same logic as the query objects themselves.  For example,
   *   PagerDefault_mysql is the MySQL-specific override for PagerDefault.
   * @return
   *   The extender object, which now contains a reference to this object.
   */
  public function extend($extender_name);
}

/**
 * Interface definition for a Select Query object.
 */
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interface SelectQueryInterface extends QueryConditionInterface, QueryAlterableInterface, QueryExtendableInterface, QueryPlaceholderInterface {
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  /* Alter accessors to expose the query data to alter hooks. */

  /**
   * Returns a reference to the fields array for this query.
   *
   * Because this method returns by reference, alter hooks may edit the fields
   * array directly to make their changes. If just adding fields, however, the
   * use of addField() is preferred.
   *
   * Note that this method must be called by reference as well:
   *
   * @code
   * $fields =& $query->getFields();
   * @endcode
   *
   * @return
   *   A reference to the fields array structure.
   */
  public function &getFields();

  /**
   * Returns a reference to the expressions array for this query.
   *
   * Because this method returns by reference, alter hooks may edit the expressions
   * array directly to make their changes. If just adding expressions, however, the
   * use of addExpression() is preferred.
   *
   * Note that this method must be called by reference as well:
   *
   * @code
   * $fields =& $query->getExpressions();
   * @endcode
   *
   * @return
   *   A reference to the expression array structure.
   */
  public function &getExpressions();

  /**
   * Returns a reference to the order by array for this query.
   *
   * Because this method returns by reference, alter hooks may edit the order-by
   * array directly to make their changes. If just adding additional ordering
   * fields, however, the use of orderBy() is preferred.
   *
   * Note that this method must be called by reference as well:
   *
   * @code
   * $fields =& $query->getOrderBy();
   * @endcode
   *
   * @return
   *   A reference to the expression array structure.
   */
  public function &getOrderBy();

  /**
   * Returns a reference to the tables array for this query.
   *
   * Because this method returns by reference, alter hooks may edit the tables
   * array directly to make their changes. If just adding tables, however, the
   * use of the join() methods is preferred.
   *
   * Note that this method must be called by reference as well:
   *
   * @code
   * $fields =& $query->getTables();
   * @endcode
   *
   * @return
   *   A reference to the tables array structure.
   */
  public function &getTables();

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  /**
   * Returns a reference to the union queries for this query. This include
   * queries for UNION, UNION ALL, and UNION DISTINCT.
   *
   * Because this method returns by reference, alter hooks may edit the tables
   * array directly to make their changes. If just adding union queries,
   * however, the use of the union() method is preferred.
   *
   * Note that this method must be called by reference as well:
   *
   * @code
   * $fields =& $query->getUnion();
   * @endcode
   *
   * @return
   *   A reference to the union query array structure.
   */
  public function &getUnion();

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  /**
   * Compiles and returns an associative array of the arguments for this prepared statement.
   *
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   * @param $queryPlaceholder
   *   When collecting the arguments of a subquery, the main placeholder
   *   object should be passed as this parameter.
   *
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   * @return
   *   An associative array of all placeholder arguments for this query.
   */
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  public function getArguments(QueryPlaceholderInterface $queryPlaceholder = NULL);
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  /* Query building operations */

  /**
   * Sets this query to be DISTINCT.
   *
   * @param $distinct
   *   TRUE to flag this query DISTINCT, FALSE to disable it.
   * @return
   *   The called object.
   */
  public function distinct($distinct = TRUE);

  /**
   * Adds a field to the list to be SELECTed.
   *
   * @param $table_alias
   *   The name of the table from which the field comes, as an alias. Generally
   *   you will want to use the return value of join() here to ensure that it is
   *   valid.
   * @param $field
   *   The name of the field.
   * @param $alias
   *   The alias for this field. If not specified, one will be generated
   *   automatically based on the $table_alias and $field. The alias will be
   *   checked for uniqueness, so the requested alias may not be the alias
   *   that is assigned in all cases.
   * @return
   *   The unique alias that was assigned for this field.
   */
  public function addField($table_alias, $field, $alias = NULL);

  /**
   * Add multiple fields from the same table to be SELECTed.
   *
   * This method does not return the aliases set for the passed fields. In the
   * majority of cases that is not a problem, as the alias will be the field
   * name. However, if you do need to know the alias you can call getFields()
   * and examine the result to determine what alias was created. Alternatively,
   * simply use addField() for the few fields you care about and this method for
   * the rest.
   *
   * @param $table_alias
   *   The name of the table from which the field comes, as an alias. Generally
   *   you will want to use the return value of join() here to ensure that it is
   *   valid.
   * @param $fields
   *   An indexed array of fields present in the specified table that should be
   *   included in this query. If not specified, $table_alias.* will be generated
   *   without any aliases.
   * @return
   *   The called object.
   */
  public function fields($table_alias, array $fields = array());

  /**
   * Adds an expression to the list of "fields" to be SELECTed.
   *
   * An expression can be any arbitrary string that is valid SQL. That includes
   * various functions, which may in some cases be database-dependent. This
   * method makes no effort to correct for database-specific functions.
   *
   * @param $expression
   *   The expression string. May contain placeholders.
   * @param $alias
   *   The alias for this expression. If not specified, one will be generated
   *   automatically in the form "expression_#". The alias will be checked for
   *   uniqueness, so the requested alias may not be the alias that is assigned
   *   in all cases.
   * @param $arguments
   *   Any placeholder arguments needed for this expression.
   * @return
   *   The unique alias that was assigned for this expression.
   */
  public function addExpression($expression, $alias = NULL, $arguments = array());

  /**
   * Default Join against another table in the database.
   *
   * This method is a convenience method for innerJoin().
   *
   * @param $table
   *   The table against which to join.
   * @param $alias
   *   The alias for the table. In most cases this should be the first letter
   *   of the table, or the first letter of each "word" in the table.
   * @param $condition
   *   The condition on which to join this table. If the join requires values,
   *   this clause should use a named placeholder and the value or values to
   *   insert should be passed in the 4th parameter. For the first table joined
   *   on a query, this value is ignored as the first table is taken as the base
   *   table.
   * @param $arguments
   *   An array of arguments to replace into the $condition of this join.
   * @return
   *   The unique alias that was assigned for this table.
   */
  public function join($table, $alias = NULL, $condition = NULL, $arguments = array());

  /**
   * Inner Join against another table in the database.
   *
   * @param $table
   *   The table against which to join.
   * @param $alias
   *   The alias for the table. In most cases this should be the first letter
   *   of the table, or the first letter of each "word" in the table.
   * @param $condition
   *   The condition on which to join this table. If the join requires values,
   *   this clause should use a named placeholder and the value or values to
   *   insert should be passed in the 4th parameter. For the first table joined
   *   on a query, this value is ignored as the first table is taken as the base
   *   table.
   * @param $arguments
   *   An array of arguments to replace into the $condition of this join.
   * @return
   *   The unique alias that was assigned for this table.
   */
  public function innerJoin($table, $alias = NULL, $condition = NULL, $arguments = array());

  /**
   * Left Outer Join against another table in the database.
   *
   * @param $table
   *   The table against which to join.
   * @param $alias
   *   The alias for the table. In most cases this should be the first letter
   *   of the table, or the first letter of each "word" in the table.
   * @param $condition
   *   The condition on which to join this table. If the join requires values,
   *   this clause should use a named placeholder and the value or values to
   *   insert should be passed in the 4th parameter. For the first table joined
   *   on a query, this value is ignored as the first table is taken as the base
   *   table.
   * @param $arguments
   *   An array of arguments to replace into the $condition of this join.
   * @return
   *   The unique alias that was assigned for this table.
   */
  public function leftJoin($table, $alias = NULL, $condition = NULL, $arguments = array());

  /**
   * Right Outer Join against another table in the database.
   *
   * @param $table
   *   The table against which to join.
   * @param $alias
   *   The alias for the table. In most cases this should be the first letter
   *   of the table, or the first letter of each "word" in the table.
   * @param $condition
   *   The condition on which to join this table. If the join requires values,
   *   this clause should use a named placeholder and the value or values to
   *   insert should be passed in the 4th parameter. For the first table joined
   *   on a query, this value is ignored as the first table is taken as the base
   *   table.
   * @param $arguments
   *   An array of arguments to replace into the $condition of this join.
   * @return
   *   The unique alias that was assigned for this table.
   */
  public function rightJoin($table, $alias = NULL, $condition = NULL, $arguments = array());

  /**
   * Join against another table in the database.
   *
   * This method does the "hard" work of queuing up a table to be joined against.
   * In some cases, that may include dipping into the Schema API to find the necessary
   * fields on which to join.
   *
   * @param $type
   *   The type of join. Typically one one of INNER, LEFT OUTER, and RIGHT OUTER.
   * @param $table
   *   The table against which to join. May be a string or another SelectQuery
   *   object. If a query object is passed, it will be used as a subselect.
   * @param $alias
   *   The alias for the table. In most cases this should be the first letter
   *   of the table, or the first letter of each "word" in the table. If omitted,
   *   one will be dynamically generated.
   * @param $condition
   *   The condition on which to join this table. If the join requires values,
   *   this clause should use a named placeholder and the value or values to
   *   insert should be passed in the 4th parameter. For the first table joined
   *   on a query, this value is ignored as the first table is taken as the base
   *   table.
   * @param $arguments
   *   An array of arguments to replace into the $condition of this join.
   * @return
   *   The unique alias that was assigned for this table.
   */
  public function addJoin($type, $table, $alias = NULL, $condition = NULL, $arguments = array());

  /**
   * Orders the result set by a given field.
   *
   * If called multiple times, the query will order by each specified field in the
   * order this method is called.
   *
   * @param $field
   *   The field on which to order.
   * @param $direction
   *   The direction to sort. Legal values are "ASC" and "DESC".
   * @return
   *   The called object.
   */
  public function orderBy($field, $direction = 'ASC');

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  /**
   * Orders the result set by a random value.
   *
   * This may be stacked with other orderBy() calls. If so, the query will order
   * by each specified field, including this one, in the order called. Although
   * this method may be called multiple times on the same query, doing so
   * is not particularly useful.
   *
   * Note: The method used by most drivers may not scale to very large result
   * sets. If you need to work with extremely large data sets, you may create
   * your own database driver by subclassing off of an existing driver and
   * implementing your own randomization mechanism. See
   *
   * http://jan.kneschke.de/projects/mysql/order-by-rand/
   *
   * for an example of such an alternate sorting mechanism.
   *
   * @return
   *   The called object
   */
  public function orderRandom();

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  /**
   * Restricts a query to a given range in the result set.
   *
   * If this method is called with no parameters, will remove any range
   * directives that have been set.
   *
   * @param $start
   *   The first record from the result set to return. If NULL, removes any
   *   range directives that are set.
   * @param $limit
   *   The number of records to return from the result set.
   * @return
   *   The called object.
   */
  public function range($start = NULL, $length = NULL);

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  /**
   * Add another Select query to UNION to this one.
   *
   * Union queries consist of two or more queries whose
   * results are effectively concatenated together. Queries
   * will be UNIONed in the order they are specified, with
   * this object's query coming first. Duplicate columns will
   * be discarded. All forms of UNION are supported, using
   * the second '$type' argument.
   *
   * Note: All queries UNIONed together must have the same
   * field structure, in the same order. It is up to the
   * caller to ensure that they match properly. If they do
   * not, an SQL syntax error will result.
   *
   * @param $query
   *   The query to UNION to this query.
   * @param $type
   *   The type of UNION to add to the query. Defaults to plain
   *   UNION.
   * @return
   *   The called object.
   */
  public function union(SelectQueryInterface $query, $type = '');

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  /**
   * Groups the result set by the specified field.
   *
   * @param $field
   *   The field on which to group. This should be the field as aliased.
   * @return
   *   The called object.
   */
  public function groupBy($field);

  /**
   * Get the equivalent COUNT query of this query as a new query object.
   *
   * @return
   *   A new SelectQuery object with no fields or expressions besides COUNT(*).
   */
  public function countQuery();

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  /**
   * Indicates if preExecute() has already been called on that object.
   */
  public function isPrepared();

  /**
   * Generic preparation and validation for a SELECT query.
   *
   * @return
   *   TRUE if the validation was successful, FALSE if not.
   */
  public function preExecute(SelectQueryInterface $query = NULL);

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  /**
   * Clone magic method.
   *
   * Select queries have dependent objects that must be deep-cloned.  The
   * connection object itself, however, should not be cloned as that would
   * duplicate the connection itself.
   */
  public function __clone();
}

/**
 * The base extender class for Select queries.
 */
class SelectQueryExtender implements SelectQueryInterface {

  /**
   * The SelectQuery object we are extending/decorating.
   *
   * @var SelectQueryInterface
   */
  protected $query;

  /**
   * The connection object on which to run this query.
   *
   * @var DatabaseConnection
   */
  protected $connection;

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  /**
   * The placeholder counter.
   */
  protected $placeholder = 0;
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  public function __construct(SelectQueryInterface $query, DatabaseConnection $connection) {
    $this->query = $query;
    $this->connection = $connection;
  }

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  /* Implementations of QueryPlaceholderInterface. */

  public function nextPlaceholder() {
    return $this->placeholder++;
  }

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  /* Implementations of QueryAlterableInterface. */

  public function addTag($tag) {
    $this->query->addTag($tag);
    return $this;
  }

  public function hasTag($tag) {
    return $this->query->hasTag($tag);
  }

  public function hasAllTags() {
    return call_user_func_array(array($this->query, 'hasAllTags', func_get_args()));
  }

  public function hasAnyTag() {
    return call_user_func_array(array($this->query, 'hasAnyTags', func_get_args()));
  }

  public function addMetaData($key, $object) {
    $this->query->addMetaData($key, $object);
    return $this;
  }

  public function getMetaData($key) {
    return $this->query->getMetaData($key);
  }

  /* Implementations of QueryConditionInterface for the WHERE clause. */

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  public function condition($field, $value = NULL, $operator = NULL) {
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    $this->query->condition($field, $value, $operator);
    return $this;
  }

  public function &conditions() {
    return $this->query->conditions();
  }

  public function arguments() {
    return $this->query->arguments();
  }

  public function where($snippet, $args = array()) {
    $this->query->where($snippet, $args);
    return $this;
  }

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  public function compile(DatabaseConnection $connection, QueryPlaceholderInterface $queryPlaceholder = NULL) {
    return $this->condition->compile($connection, isset($queryPlaceholder) ? $queryPlaceholder : $this);
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  }

  /* Implmeentations of QueryConditionInterface for the HAVING clause. */

  public function havingCondition($field, $value = NULL, $operator = '=') {
    $this->query->condition($field, $value, $operator, $num_args);
    return $this;
  }

  public function &havingConditions() {
    return $this->having->conditions();
  }

  public function havingArguments() {
    return $this->having->arguments();
  }

  public function having($snippet, $args = array()) {
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    $this->query->having($snippet, $args);
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    return $this;
  }

  public function havingCompile(DatabaseConnection $connection) {
    return $this->query->havingCompile($connection);
  }

  /* Implementations of QueryExtendableInterface. */

  public function extend($extender_name) {
    $override_class = $this->connection->driver();
    if (class_exists($override_class)) {
      $extender_name = $override_class;
    }
    return new $extender_name($this, $this->connection);
  }

  /* Alter accessors to expose the query data to alter hooks. */

  public function &getFields() {
    return $this->query->getFields();
  }

  public function &getExpressions() {
    return $this->query->getExpressions();
  }

  public function &getOrderBy() {
    return $this->query->getOrderBy();
  }

  public function &getTables() {
    return $this->query->getTables();
  }

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  public function &getUnion() {
    return $this->query->getUnion();
  }

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  public function getArguments(QueryPlaceholderInterface $queryPlaceholder = NULL) {
    return $this->query->getArguments($queryPlaceholder);
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  }

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  public function isPrepared() {
    return $this->query->isPrepared();
  }

  public function preExecute(SelectQueryInterface $query = NULL) {
    // If no query object is passed in, use $this.
    if (is_null($query)) {
      $query = $this;
    }

    return $this->query->preExecute($query);
  }

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  public function execute() {
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    // By calling preExecute() here, we force it to preprocess the extender
    // object rather than just the base query object.  That means
    // hook_query_alter() gets access to the extended object.
    if (!$this->preExecute($this)) {
      return NULL;
    }

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    return $this->query->execute();
  }

  public function distinct($distinct = TRUE) {
    $this->query->distinct($distinct);
    return $this;
  }

  public function addField($table_alias, $field, $alias = NULL) {
    return $this->query->addField($table_alias, $field, $alias);
  }

  public function fields($table_alias, array $fields = array()) {
    $this->query->fields($table_alias, $fields);
    return $this;
  }

  public function addExpression($expression, $alias = NULL, $arguments = array()) {
    return $this->query->addExpression($expression, $alias, $arguments);
  }

  public function join($table, $alias = NULL, $condition = NULL, $arguments = array()) {
    return $this->query->join($table, $alias, $condition, $arguments);
  }

  public function innerJoin($table, $alias = NULL, $condition = NULL, $arguments = array()) {
    return $this->query->innerJoin($table, $alias, $condition, $arguments);
  }

  public function leftJoin($table, $alias = NULL, $condition = NULL, $arguments = array()) {
    return $this->query->leftJoin($table, $alias, $condition, $arguments);
  }

  public function rightJoin($table, $alias = NULL, $condition = NULL, $arguments = array()) {
    return $this->query->rightJoin($table, $alias, $condition, $arguments);
  }

  public function addJoin($type, $table, $alias = NULL, $condition = NULL, $arguments = array()) {
    return $this->query->addJoin($type, $table, $alias, $condition, $arguments);
  }

  public function orderBy($field, $direction = 'ASC') {
    $this->query->orderBy($field, $direction);
    return $this;
  }

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  public function orderRandom() {
    $this->query->orderRandom();
    return $this;
  }

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  public function range($start = NULL, $length = NULL) {
    $this->query->range($start, $length);
    return $this;
  }

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  public function union(SelectQueryInterface $query, $type = '') {
    $this->query->union($query, $type);
    return $this;
  }

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  public function groupBy($field) {
    $this->query->groupBy($field);
    return $this;
  }

  public function countQuery() {
    // Create our new query object that we will mutate into a count query.
    $count = clone($this);

    // Zero-out existing fields and expressions.
    $fields =& $count->getFields();
    $fields = array();
    $expressions =& $count->getExpressions();
    $expressions = array();

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    // Also remove 'all_fields' statements, which are expanded into tablename.*
    // when the query is executed.
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    $tables = &$count->getTables();
    foreach ($tables as $alias => &$table) {
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      unset($table['all_fields']);
    }

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    // Ordering a count query is a waste of cycles, and breaks on some
    // databases anyway.
    $orders = &$count->getOrderBy();
    $orders = array();

    // COUNT() is an expression, so we add that back in.
    $count->addExpression('COUNT(*)');

    return $count;
  }

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  function isNull($field) {
    $this->query->isNull($field);
    return $this;
  }

  function isNotNull($field) {
    $this->query->isNotNull($field);
    return $this;
  }

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  public function __toString() {
    return (string)$this->query;
  }

  public function __clone() {
    // We need to deep-clone the query we're wrapping, which in turn may
    // deep-clone other objects.  Exciting!
    $this->query = clone($this->query);
  }

  /**
   * Magic override for undefined methods.
   *
   * If one extender extends another extender, then methods in the inner extender
   * will not be exposed on the outer extender.  That's because we cannot know
   * in advance what those methods will be, so we cannot provide wrapping
   * implementations as we do above.  Instead, we use this slower catch-all method
   * to handle any additional methods.
   */
  public function __call($method, $args) {
    $return = call_user_func_array(array($this->query, $method), $args);

    // Some methods will return the called object as part of a fluent interface.
    // Others will return some useful value.  If it's a value, then the caller
    // probably wants that value.  If it's the called object, then we instead
    // return this object.  That way we don't "lose" an extender layer when
    // chaining methods together.
    if ($return instanceof SelectQueryInterface) {
      return $this;
    }
    else {
      return $return;
    }
  }
}

762 763 764
/**
 * Query builder for SELECT statements.
 */
765
class SelectQuery extends Query implements SelectQueryInterface {
766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783

  /**
   * The fields to SELECT.
   *
   * @var array
   */
  protected $fields = array();

  /**
   * The expressions to SELECT as virtual fields.
   *
   * @var array
   */
  protected $expressions = array();

  /**
   * The tables against which to JOIN.
   *
784 785
   * This property is a nested array. Each entry is an array representing
   * a single table against which to join. The structure of each entry is:
786 787 788
   *
   * array(
   *   'type' => $join_type (one of INNER, LEFT OUTER, RIGHT OUTER),
789
   *   'table' => $table,
790 791 792
   *   'alias' => $alias_of_the_table,
   *   'condition' => $condition_clause_on_which_to_join,
   *   'arguments' => $array_of_arguments_for_placeholders_in_the condition.
793
   *   'all_fields' => TRUE to SELECT $alias.*, FALSE or NULL otherwise.
794 795
   * )
   *
796
   * If $table is a string, it is taken as the name of a table. If it is
797 798
   * a SelectQuery object, it is taken as a subquery.
   *
799 800 801 802 803 804 805
   * @var array
   */
  protected $tables = array();

  /**
   * The fields by which to order this query.
   *
806
   * This is an associative array. The keys are the fields to order, and the value
807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847
   * is the direction to order, either ASC or DESC.
   *
   * @var array
   */
  protected $order = array();

  /**
   * The fields by which to group.
   *
   * @var array
   */
  protected $group = array();

  /**
   * The conditional object for the WHERE clause.
   *
   * @var DatabaseCondition
   */
  protected $where;

  /**
   * The conditional object for the HAVING clause.
   *
   * @var DatabaseCondition
   */
  protected $having;

  /**
   * Whether or not this query should be DISTINCT
   *
   * @var boolean
   */
  protected $distinct = FALSE;

  /**
   * The range limiters for this query.
   *
   * @var array
   */
  protected $range;

848 849 850 851 852 853 854 855 856 857 858 859 860
  /**
   * 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' statement, respectively.
   *
   * All entries in this array will be applied from front to back, with the
   * first query to union on the right of the original query, the second union
   * to the right of the first, etc.
   *
   * @var array
   */
  protected $union = array();

861 862 863 864 865 866
  /**
   * Indicates if preExecute() has already been called.
   * @var boolean
   */
  protected $prepared = FALSE;

867 868 869 870 871 872 873
  public function __construct($table, $alias = NULL, DatabaseConnection $connection, $options = array()) {
    $options['return'] = Database::RETURN_STATEMENT;
    parent::__construct($connection, $options);
    $this->where = new DatabaseCondition('AND');
    $this->having = new DatabaseCondition('AND');
    $this->addJoin(NULL, $table, $alias);
  }
874

875
  /* Implementations of QueryAlterableInterface. */
876

877 878
  public function addTag($tag) {
    $this->alterTags[$tag] = 1;
879
    return $this;
880
  }
881

882 883 884
  public function hasTag($tag) {
    return isset($this->alterTags[$tag]);
  }
885

886 887 888
  public function hasAllTags() {
    return !(boolean)array_diff(func_get_args(), array_keys($this->alterTags));
  }
889

890 891 892
  public function hasAnyTag() {
    return (boolean)array_intersect(func_get_args(), array_keys($this->alterTags));
  }
893

894 895
  public function addMetaData($key, $object) {
    $this->alterMetaData[$key] = $object;
896
    return $this;
897
  }
898

899 900 901
  public function getMetaData($key) {
    return isset($this->alterMetaData[$key]) ? $this->alterMetaData[$key] : NULL;
  }
902

903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924
  /* Implementations of QueryConditionInterface for the WHERE clause. */

  public function condition($field, $value = NULL, $operator = '=') {
    if (!isset($num_args)) {
      $num_args = func_num_args();
    }
    $this->where->condition($field, $value, $operator, $num_args);
    return $this;
  }

  public function &conditions() {
    return $this->where->conditions();
  }

  public function arguments() {
    return $this->where->arguments();
  }

  public function where($snippet, $args = array()) {
    $this->where->where($snippet, $args);
    return $this;
  }
925

926 927 928 929 930 931 932 933 934 935
  public function isNull($field) {
    $this->where->isNull($field);
    return $this;
  }

  public function isNotNull($field) {
    $this->where->isNotNull($field);
    return $this;
  }

936 937
  public function compile(DatabaseConnection $connection, QueryPlaceholderInterface $queryPlaceholder = NULL) {
    return $this->where->compile($connection, isset($queryPlaceholder) ? $queryPlaceholder : $this);
938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961
  }

  /* Implmeentations of QueryConditionInterface for the HAVING clause. */

  public function havingCondition($field, $value = NULL, $operator = '=') {
    if (!isset($num_args)) {
      $num_args = func_num_args();
    }
    $this->having->condition($field, $value, $operator, $num_args);
    return $this;
  }

  public function &havingConditions() {
    return $this->having->conditions();
  }

  public function havingArguments() {
    return $this->having->arguments();
  }

  public function having($snippet, $args = array()) {
    $this->having->where($snippet, $args);
    return $this;
  }
962

963
  public function havingCompile(DatabaseConnection $connection) {
964
    return $this->having->compile($connection, $this);
965 966
  }

967 968 969 970 971 972 973 974 975 976
  /* Implementations of QueryExtendableInterface. */

  public function extend($extender_name) {
    $override_class = __CLASS__ . $this->connection->driver();
    if (class_exists($override_class)) {
      $extender_name = $override_class;
    }
    return new $extender_name($this, $this->connection);
  }

977 978 979 980 981 982 983 984 985 986 987
  public function havingIsNull($field) {
    $this->having->isNull($field);
    return $this;
  }

  public function havingIsNotNull($field) {
    $this->having->isNotNull($field);
    return $this;
  }


988
  /* Alter accessors to expose the query data to alter hooks. */
989

990 991
  public function &getFields() {
    return $this->fields;
992 993
  }

994 995 996
  public function &getExpressions() {
    return $this->expressions;
  }
997

998 999 1000
  public function &getOrderBy() {
    return $this->order;
  }
1001

1002 1003 1004 1005
  public function &getTables() {
    return $this->tables;
  }

1006 1007 1008 1009
  public function &getUnion() {
    return $this->union;
  }

1010 1011 1012 1013 1014 1015
  public function getArguments(QueryPlaceholderInterface $queryPlaceholder = NULL) {
    if (!isset($queryPlaceholder)) {
      $queryPlaceholder = $this;
    }
    $this->where->compile($this->connection, $queryPlaceholder);
    $this->having->compile($this->connection, $queryPlaceholder);
1016
    $args = $this->where->arguments() + $this->having->arguments();
1017

1018 1019 1020 1021
    foreach ($this->tables as $table) {
      if ($table['arguments']) {
        $args += $table['arguments'];
      }
1022
      // If this table is a subquery, grab its arguments recursively.
1023
      if ($table['table'] instanceof SelectQueryInterface) {
1024
        $args += $table['table']->getArguments($queryPlaceholder);
1025
      }
1026
    }
1027

1028 1029 1030 1031 1032
    foreach ($this->expressions as $expression) {
      if ($expression['arguments']) {
        $args += $expression['arguments'];
      }
    }
1033

1034 1035 1036 1037 1038 1039
    // If there are any dependent queries to UNION,
    // incorporate their arguments recursively.
    foreach ($this->union as $union) {
      $args += $union['query']->getArguments($queryPlaceholder);
    }

1040 1041
    return $args;
  }
1042

1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066
  /**
   * Indicates if preExecute() has already been called on that object.
   */
  public function isPrepared() {
    return $this->prepared;
  }

  /**
   * Generic preparation and validation for a SELECT query.
   *
   * @return
   *   TRUE if the validation was successful, FALSE if not.
   */
  public function preExecute(SelectQueryInterface $query = NULL) {
    // If no query object is passed in, use $this.
    if (is_null($query)) {
      $query = $this;
    }

    // Only execute this once.
    if ($query->isPrepared()) {
      return TRUE;
    }

1067
    // Modules may alter all queries or only those having a particular tag.
1068
    drupal_alter('query', $query);
1069 1070
    if (isset($this->alterTags)) {
      foreach ($this->alterTags as $tag => $value) {
1071
        drupal_alter("query_$tag", $query);
1072 1073
      }
    }
1074 1075 1076 1077 1078 1079 1080 1081 1082
    return $this->prepared = TRUE;
  }

  public function execute() {
    // If validation fails, simply return NULL.
    // Note that validation routines in preExecute() may throw exceptions instead.
    if (!$this->preExecute()) {
      return NULL;
    }
1083

1084
    $args = $this->getArguments();
1085

1086
    if (!empty($this->range)) {
1087
      return $this->connection->queryRange((string)$this, $this->range['start'], $this->range['length'], $args, $this->queryOptions);
1088 1089 1090 1091 1092 1093 1094 1095 1096 1097
    }
    return $this->connection->query((string)$this, $args, $this->queryOptions);
  }

  public function distinct($distinct = TRUE) {
    $this->distinct = $distinct;
    return $this;
  }

  public function addField($table_alias, $field, $alias = NULL) {
1098
    // If no alias is specified, first try the field name itself.
1099
    if (empty($alias)) {
1100 1101 1102 1103 1104
      $alias = $field;
    }

    // If that's already in use, try the table name and field name.
    if (!empty($this->tables[$alias])) {
1105 1106 1107
      $alias = $table_alias . '_' . $field;
    }

1108
    // If that is already used, just add a counter until we find an unused alias.
1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124
    $alias_candidate = $alias;
    $count = 2;
    while (!empty($this->tables[$alias_candidate])) {
      $alias_candidate = $alias . '_' . $count++;
    }
    $alias = $alias_candidate;

    $this->fields[$alias] = array(
      'field' => $field,
      'table' => $table_alias,
      'alias' => $alias,
    );

    return $alias;
  }

1125
  public function fields($table_alias, array $fields = array()) {
1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140

    if ($fields) {
      foreach ($fields as $field) {
        // We don't care what alias was assigned.
        $this->addField($table_alias, $field);
      }
    }
    else {
      // We want all fields from this table.
      $this->tables[$table_alias]['all_fields'] = TRUE;
    }

    return $this;
  }

1141 1142 1143 1144
  public function addExpression($expression, $alias = NULL, $arguments = array()) {
    if (empty($alias)) {
      $alias = 'expression';
    }
1145

1146 1147 1148 1149
    $alias_candidate = $alias;
    $count = 2;
    while (!empty($this->expressions[$alias_candidate])) {
      $alias_candidate = $alias . '_' . $count++;
1150
    }
1151
    $alias = $alias_candidate;
1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180

    $this->expressions[$alias] = array(
      'expression' => $expression,
      'alias' => $alias,
      'arguments' => $arguments,
    );

    return $alias;
  }

  public function join($table, $alias = NULL, $condition = NULL, $arguments = array()) {
    return $this->addJoin('INNER', $table, $alias, $condition, $arguments);
  }

  public function innerJoin($table, $alias = NULL, $condition = NULL, $arguments = array()) {
    return $this->addJoin('INNER', $table, $alias, $condition, $arguments);
  }

  public function leftJoin($table, $alias = NULL, $condition = NULL, $arguments = array()) {
    return $this->addJoin('LEFT OUTER', $table, $alias, $condition, $arguments);
  }

  public function rightJoin($table, $alias = NULL, $condition = NULL, $arguments = array()) {
    return $this->addJoin('RIGHT OUTER', $table, $alias, $condition, $arguments);
  }

  public function addJoin($type, $table, $alias = NULL, $condition = NULL, $arguments = array()) {

    if (empty($alias)) {
1181
      if ($table instanceof SelectQueryInterface) {
1182 1183 1184 1185 1186
        $alias = 'subquery';
      }
      else {
        $alias = $table;
      }
1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211
    }

    $alias_candidate = $alias;
    $count = 2;
    while (!empty($this->tables[$alias_candidate])) {
      $alias_candidate = $alias . '_' . $count++;
    }
    $alias = $alias_candidate;

    $this->tables[$alias] = array(
      'join type' => $type,
      'table' => $table,
      'alias' => $alias,
      'condition' => $condition,
      'arguments' => $arguments,
    );

    return $alias;
  }

  public function orderBy($field, $direction = 'ASC') {
    $this->order[$field] = $direction;
    return $this;
  }

1212 1213 1214 1215 1216 1217
  public function orderRandom() {
    $alias = $this->addExpression('RAND()', 'random_field');
    $this->orderBy($alias);
    return $this;
  }

1218 1219 1220 1221 1222
  public function range($start = NULL, $length = NULL) {
    $this->range = func_num_args() ? array('start' => $start, 'length' => $length) : array();
    return $this;
  }

1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244
  public function union(SelectQueryInterface $query, $type = '') {
    // Handle UNION aliasing.
    switch ($type) {
      // Fold UNION DISTINCT to UNION for better cross database support.
      case 'DISTINCT':
      case '':
        $type = 'UNION';
        break;
      
      case 'ALL':
        $type = 'UNION ALL';
      default:
    }

    $this->union[] = array(
      'type' => $type,
      'query' => $query,
    );

    return $this;
  }

1245 1246
  public function groupBy($field) {
    $this->group[] = $field;
1247
    return $this;
1248
  }
1249

1250
  public function countQuery() {
1251
    // Create our new query object that we will mutate into a count query.
1252
    $count = clone($this);
1253

1254 1255 1256 1257 1258
    // Zero-out existing fields and expressions.
    $fields =& $count->getFields();
    $fields = array();
    $expressions =& $count->getExpressions();
    $expressions = array();
1259

1260 1261 1262 1263 1264 1265 1266

    // Also remove 'all_fields' statements, which are expanded into tablename.*
    // when the query is executed.
    foreach ($count->tables as $alias => &$table) {
      unset($table['all_fields']);
    }

1267 1268 1269 1270
    // Ordering a count query is a waste of cycles, and breaks on some
    // databases anyway.
    $orders = &$count->getOrderBy();
    $orders = array();
1271

1272 1273
    // COUNT() is an expression, so we add that back in.
    $count->addExpression('COUNT(*)');
1274

1275 1276
    return $count;
  }
1277

1278 1279 1280 1281 1282 1283 1284 1285 1286 1287
  public function __toString() {

    // SELECT
    $query = 'SELECT ';
    if ($this->distinct) {
      $query .= 'DISTINCT ';
    }

    // FIELDS and EXPRESSIONS
    $fields = array();
1288 1289 1290 1291 1292
    foreach ($this->tables as $alias => $table) {
      if (!empty($table['all_fields'])) {
        $fields[] = $alias . '.*';
      }
    }
1293
    foreach ($this->fields as $alias => $field) {
1294 1295
      // Always use the AS keyword for field aliases, as some
      // databases require it (e.g., PostgreSQL).
1296 1297 1298 1299 1300 1301 1302
      $fields[] = (isset($field['table']) ? $field['table'] . '.' : '') . $field['field'] . ' AS ' . $field['alias'];
    }
    foreach ($this->expressions as $alias => $expression) {
      $fields[] = $expression['expression'] . ' AS ' . $expression['alias'];
    }
    $query .= implode(', ', $fields);

1303

1304 1305 1306 1307 1308 1309 1310
    // FROM - We presume all queries have a FROM, as any query that doesn't won't need the query builder anyway.
    $query .= "\nFROM ";
    foreach ($this->tables as $alias => $table) {
      $query .= "\n";
      if (isset($table['join type'])) {
        $query .= $table['join type'] . ' JOIN ';
      }
1311 1312

      // If the table is a subquery, compile it and integrate it into this query.
1313
      if ($table['table'] instanceof SelectQueryInterface) {
1314
        $table_string = '(' . (string)$table['table'] . ')';
1315 1316 1317 1318 1319
      }
      else {
        $table_string = '{' . $this->connection->escapeTable($table['table']) . '}';
      }

1320 1321
      // Don't use the AS keyword for table aliases, as some
      // databases don't support it (e.g., Oracle).
1322 1323
      $query .=  $table_string . ' ' . $table['alias'];

1324 1325 1326 1327 1328 1329 1330
      if (!empty($table['condition'])) {
        $query .= ' ON ' . $table['condition'];
      }
    }

    // WHERE
    if (count($this->where)) {
1331
      $this->where->compile($this->connection, $this);
1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342
      // There is an implicit string cast on $this->condition.
      $query .= "\nWHERE " . $this->where;
    }

    // GROUP BY
    if ($this->group) {
      $query .= "\nGROUP BY " . implode(', ', $this->group);
    }

    // HAVING
    if (count($this->having)) {
1343
      $this->having->compile($this->connection, $this);
1344 1345 1346 1347 1348 1349 1350
      // There is an implicit string cast on $this->having.
      $query .= "\nHAVING " . $this->having;
    }

    // ORDER BY
    if ($this->order) {
      $query .= "\nORDER BY ";
1351
      $fields = array();
1352
      foreach ($this->order as $field => $direction) {
1353
        $fields[] = $field . ' ' . $direction;
1354
      }
1355
      $query .= implode(', ', $fields);
1356 1357 1358
    }

    // RANGE is database specific, so we can't do it here.
1359 1360 1361 1362 1363 1364 1365 1366 1367

    // UNION is a little odd, as the select queries to combine are passed into
    // this query, but syntactically they all end up on the same level.
    if ($this->union) {
      foreach ($this->union as $union) {
        $query .= ' ' . $union['type'] . ' ' . (string) $union['query'];
      }
    }

1368 1369
    return $query;
  }
1370

1371
  public function __clone() {
1372
    // On cloning, also clone the dependent objects. However, we do not
1373 1374
    // want to clone the database connection object as that would duplicate the
    // connection itself.
1375

1376 1377
    $this->where = clone($this->where);
    $this->having = clone($this->having);
1378 1379 1380
    foreach ($this->union as $key => $aggregate) {
      $this->union[$key]['query'] = clone($aggregate['query']);
    }
1381 1382 1383 1384 1385 1386
  }
}

/**
 * @} End of "ingroup database".
 */