Fixes #5223: Query builder now supports selecting sub-queries as columns

docs/guide/db-query-builder.md

@@ -85,6 +85,15 @@ When specifying columns, you may include the table prefixes or column aliases, e
 If you are using array to specify the columns, you may also use the array keys to specify the column aliases,
 e.g., `['user_id' => 'user.id', 'user_name' => 'user.name']`.
 
+Starting from version 2.0.1, you may also select sub-queries as columns. For example,
+ 
+```php
+$subQuery = (new Query)->select('COUNT(*)')->from('user');
+$query = (new Query)->select(['id', 'count' => $subQuery])->from('post');
+// $query represents the following SQL:
+// SELECT `id`, (SELECT COUNT(*) FROM `user`) AS `count` FROM `post`
+```
+
 To select distinct rows, you may call `distinct()`, like the following:
 
 ```php

extensions/sphinx/CHANGELOG.md

@@ -5,6 +5,7 @@ Yii Framework 2 sphinx extension Change Log
 -----------------------
 
 - Bug #5601: Simple conditions in Query::where() and ActiveQuery::where() did not allow `yii\db\Expression` to be used as the value (cebe, stevekr)
+- Enh #5223: Query builder now supports selecting sub-queries as columns (qiangxue)
 
 
 2.0.0 October 12, 2014

extensions/sphinx/QueryBuilder.php

@@ -446,6 +446,9 @@ class QueryBuilder extends Object
             if ($column instanceof Expression) {
                 $columns[$i] = $column->expression;
                 $params = array_merge($params, $column->params);
+            } elseif ($column instanceof Query) {
+                list($sql, $params) = $this->build($column, $params);
+                $columns[$i] = "($sql) AS " . $this->db->quoteColumnName($i);
             } elseif (is_string($i)) {
                 if (strpos($column, '(') === false) {
                     $column = $this->db->quoteColumnName($column);

framework/CHANGELOG.md

@@ -8,13 +8,13 @@ Yii Framework 2 Change Log
 - Bug #5584: `yii\rbac\DbRbacManager` should not delete items when deleting a rule on a database not supporting cascade update (mdmunir)
 - Bug #5601: Simple conditions in Query::where() and ActiveQuery::where() did not allow `yii\db\Expression` to be used as the value (cebe, stevekr)
 - Bug: Gii console command help information does not contain global options (qiangxue)
+- Enh #5223: Query builder now supports selecting sub-queries as columns (qiangxue)
 - Enh #5587: `json_encode` is now used with `JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE` where it makes sense, also
   it is now default for `Json::encode()` (samdark)
 - Enh #5600: Allow configuring debug panels in `yii\debug\Module::panels` as panel class name strings (qiangxue)
 - Enh #5613: Added `--overwrite` option to Gii console command to support overwriting all files (motin, qiangxue)
 - Enh #5646: Call `yii\base\ErrorHandler::unregister()` instead of `restore_*_handlers` directly (aivus)
 
-
 2.0.0 October 12, 2014
 ----------------------
 

framework/db/QueryBuilder.php

@@ -626,6 +626,9 @@ class QueryBuilder extends \yii\base\Object
             if ($column instanceof Expression) {
                 $columns[$i] = $column->expression;
                 $params = array_merge($params, $column->params);
+            } elseif ($column instanceof Query) {
+                list($sql, $params) = $this->build($column, $params);
+                $columns[$i] = "($sql) AS " . $this->db->quoteColumnName($i);
             } elseif (is_string($i)) {
                 if (strpos($column, '(') === false) {
                     $column = $this->db->quoteColumnName($column);

tests/unit/framework/db/QueryBuilderTest.php

@@ -422,4 +422,20 @@ class QueryBuilderTest extends DatabaseTestCase
         list($actualQuerySql, $queryParams) = $this->getQueryBuilder()->build($query);
         $this->assertEquals($expectedQuerySql, $actualQuerySql);
     }
+
+    public function testSelectSubquery()
+    {
+        $subquery = (new Query())
+            ->select('COUNT(*)')
+            ->from('operations')
+            ->where('account_id = accounts.id');
+        $query = (new Query())
+            ->select('*')
+            ->from('accounts')
+            ->addSelect(['operations_count' => $subquery]);
+        list ($sql, $params) = $this->getQueryBuilder()->build($query);
+        $expected = 'SELECT *, (SELECT COUNT(*) FROM `operations` WHERE account_id = accounts.id) AS `operations_count` FROM `accounts`';
+        $this->assertEquals($expected, $sql);
+        $this->assertEmpty($params);
+    }
 }