From d4a597fd4bb2713b8f828211db6caa1b44c46faf Mon Sep 17 00:00:00 2001
From: Angie Byron <webchick@24967.no-reply.drupal.org>
Date: Fri, 11 Sep 2009 02:47:11 +0000
Subject: #561104 by Crell: Added support for random ordering in dynamic select
 queries.

---
 includes/database/pgsql/query.inc | 10 ++++++++++
 includes/database/select.inc      | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+)

(limited to 'includes/database')

diff --git a/includes/database/pgsql/query.inc b/includes/database/pgsql/query.inc
index 9005a1a83..ac5072c76 100644
--- a/includes/database/pgsql/query.inc
+++ b/includes/database/pgsql/query.inc
@@ -173,3 +173,13 @@ class UpdateQuery_pgsql extends UpdateQuery {
     return $stmt->rowCount();
   }
 }
+
+class SelectQuery_pgsql extends SelectQuery {
+
+  public function orderRandom() {
+    $alias = $this->addExpression('RANDOM()', 'random_field');
+    $this->orderBy($alias);
+    return $this;
+  }
+
+}
diff --git a/includes/database/select.inc b/includes/database/select.inc
index a4c4ed3e4..55eecf586 100644
--- a/includes/database/select.inc
+++ b/includes/database/select.inc
@@ -347,6 +347,28 @@ interface SelectQueryInterface extends QueryConditionInterface, QueryAlterableIn
    */
   public function orderBy($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
+   *   The called object
+   */
+  public function orderRandom();
+
   /**
    * Restricts a query to a given range in the result set.
    *
@@ -643,6 +665,11 @@ class SelectQueryExtender implements SelectQueryInterface {
     return $this;
   }
 
+  public function orderRandom() {
+    $this->query->orderRandom();
+    return $this;
+  }
+
   public function range($start = NULL, $length = NULL) {
     $this->query->range($start, $length);
     return $this;
@@ -1182,6 +1209,12 @@ class SelectQuery extends Query implements SelectQueryInterface {
     return $this;
   }
 
+  public function orderRandom() {
+    $alias = $this->addExpression('RAND()', 'random_field');
+    $this->orderBy($alias);
+    return $this;
+  }
+
   public function range($start = NULL, $length = NULL) {
     $this->range = func_num_args() ? array('start' => $start, 'length' => $length) : array();
     return $this;
-- 
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