- Patch #369314 by Berdir: make sub-selects work.

includes/database/query.inc

@@ -1179,6 +1179,7 @@ public function compile(DatabaseConnection $connection) {
             }
             $operator += $operator_defaults;
 
+            $placeholders = array();
             if ($condition['value'] instanceof SelectQuery) {
               $placeholders[] = (string)$condition['value'];
               $arguments += $condition['value']->arguments();
@@ -1189,7 +1190,6 @@ public function compile(DatabaseConnection $connection) {
             elseif (!$operator['delimiter']) {
               $condition['value'] = array($condition['value']);
             }
-            $placeholders = array();
             if ($operator['use_value']) {
               foreach ($condition['value'] as $value) {
                 $placeholder = ':db_condition_placeholder_' . $next_placeholder++;

modules/simpletest/tests/database_test.test

@@ -1364,6 +1364,29 @@ class DatabaseSelectSubqueryTestCase extends DatabaseTestCase {
     $this->assertEqual(count($people), 1, t('Returned the correct number of rows.'));
   }
 
+  /**
+   * Test that we can use a subquery in a FROM clause.
+   */
+  function testConditionSubquerySelect() {
+    // Create a subquery, which is just a normal query object.
+    $subquery = db_select('test_task', 'tt');
+    $subquery->addField('tt', 'pid', 'pid');
+    $subquery->condition('tt.priority', 1);
+
+    // Create another query that joins against the virtual table resulting
+    // from the subquery.
+    $select = db_select('test_task', 'tt2');
+    $select->addField('tt2', 'task');
+    $select->condition('tt2.pid', $subquery, 'IN');
+
+    // The resulting query should be equivalent to:
+    // SELECT tt2.name
+    // FROM test tt2
+    // WHERE tt2.pid IN (SELECT tt.pid AS pid FROM test_task tt WHERE tt.priority=1)
+    $people = $select->execute()->fetchCol();
+    $this->assertEqual(count($people), 5, t('Returned the correct number of rows.'));
+  }
+
   /**
    * Test that we can use a subquery in a JOIN clause.
    */