Fixes #2490: `yii\db\Query::count()` and other query scalar methods now properly…

framework/CHANGELOG.md

@@ -116,6 +116,7 @@ Yii Framework 2 Change Log
 - Enh #2417: Added possibility to set `dataType` for `$.ajax` call in yii.activeForm.js (Borales)
 - Enh #2436: Label of the attribute, which looks like `relatedModel.attribute`, will be received from the related model if it available (djagya)
 - Enh #2415: Added support for inverse relations (qiangxue)
+- Enh #2490: `yii\db\Query::count()` and other query scalar methods now properly handle queries with GROUP BY clause (qiangxue)
 - Enh: Added support for using arrays as option values for console commands (qiangxue)
 - Enh: Added `favicon.ico` and `robots.txt` to default application templates (samdark)
 - Enh: Added `Widget::autoIdPrefix` to support prefixing automatically generated widget IDs (qiangxue)

framework/db/Query.php

@@ -356,7 +356,14 @@ class Query extends Component implements QueryInterface
 		$this->limit = $limit;
 		$this->offset = $offset;
 
+		if (empty($this->groupBy)) {
 			return $command->queryScalar();
+		} else {
+			return (new Query)->select([$selectExpression])
+				->from(['c' => $this])
+				->createCommand($db)
+				->queryScalar();
+		}
 	}
 
 	/**