<?php

/**

 * @addtogroup database

 * @{

 */

require_once dirname(__FILE__) . '/query.inc';

/**

 * 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 QueryExtendableInterface

   *   The extender object, which now contains a reference to this object.

   */

  public function extend($extender_name);

}

/**

 * Interface definition for a Select Query object.

 */

interface SelectQueryInterface extends QueryConditionInterface, QueryAlterableInterface, QueryExtendableInterface, QueryPlaceholderInterface {

  /* 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 group-by array for this query.

   *

   * Because this method returns by reference, alter hooks may edit the group-by

   * array directly to make their changes. If just adding additional grouping

   * fields, however, the use of groupBy() is preferred.

   *

   * Note that this method must be called by reference as well:

   *

   * @code

   * $fields =& $query->getGroupBy();

   * @endcode

   *

   * @return

   *   A reference to the group-by array structure.

   */

  public function &getGroupBy();

  /**

   * 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();

  /**

   * 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();

  /**

   * Compiles and returns an associative array of the arguments for this prepared statement.

   *

   * @param $queryPlaceholder

   *   When collecting the arguments of a subquery, the main placeholder

   *   object should be passed as this parameter.

   *

   * @return

   *   An associative array of all placeholder arguments for this query.

   */

  public function getArguments(QueryPlaceholderInterface $queryPlaceholder = NULL);

  /* Query building operations */

  /**

   * Sets this query to be DISTINCT.

   *

   * @param $distinct

   *   TRUE to flag this query DISTINCT, FALSE to disable it.

   * @return SelectQueryInterface

   *   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 SelectQueryInterface

   *   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. The token %alias can be used in this string to be replaced with

   *   the actual alias. This is useful when $alias is modified by the database

   *   system, for example, when joining the same table more than once.

   * @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. The token %alias can be used in this string to be replaced with

   *   the actual alias. This is useful when $alias is modified by the database

   *   system, for example, when joining the same table more than once.

   * @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. The token %alias can be used in this string to be replaced with

   *   the actual alias. This is useful when $alias is modified by the database

   *   system, for example, when joining the same table more than once.

   * @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. The token %alias can be used in this string to be replaced with

   *   the actual alias. This is useful when $alias is modified by the database

   *   system, for example, when joining the same table more than once.

   * @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. The token %alias can be used in this string to be replaced with

   *   the actual alias. This is useful when $alias is modified by the database

   *   system, for example, when joining the same table more than once.

   * @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.

   *

   * If the query uses DISTINCT or GROUP BY conditions, fields or expressions

   * that are used for the order must be selected to be compatible with some

   * databases like PostgreSQL. The PostgreSQL driver can handle simple cases

   * automatically but it is suggested to explicitly specify them. Additionally,

   * when ordering on an alias, the alias must be added before orderBy() is

   * called.

   *

   * @param $field

   *   The field on which to order.

   * @param $direction

   *   The direction to sort. Legal values are "ASC" and "DESC". Any other value

   *   will be converted to "ASC".

   * @return SelectQueryInterface

   *   The called object.

   */

  public function orderBy($field, $direction = 'ASC');

  /**

   * 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 SelectQueryInterface

   *   The called object

   */

  public function orderRandom();

  /**

   * 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 $length

   *   The number of records to return from the result set.

   * @return SelectQueryInterface

   *   The called object.

   */

  public function range($start = NULL, $length = NULL);

  /**

   * 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 SelectQueryInterface

   *   The called object.

   */

  public function union(SelectQueryInterface $query, $type = '');

  /**

   * Groups the result set by the specified field.

   *

   * @param $field

   *   The field on which to group. This should be the field as aliased.

   * @return SelectQueryInterface

   *   The called object.

   */

  public function groupBy($field);

  /**

   * Get the equivalent COUNT query of this query as a new query object.

   *

   * @return SelectQueryInterface

   *   A new SelectQuery object with no fields or expressions besides COUNT(*).

   */

  public function countQuery();

  /**

   * Indicates if preExecute() has already been called on that object.

   *

   * @return

   *   TRUE is this query has already been prepared, FALSE otherwise.

   */

  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);