Updated code styling and added braces.

framework/yii/db/QueryBuilder.php

@@ -278,10 +278,14 @@ class QueryBuilder extends \yii\base\Object
 	 */
 	public function addPrimaryKey($name, $table, $columns)
 	{
-		if(is_string($columns))
+		if (is_string($columns)) {
 			$columns=preg_split('/\s*,\s*/',$columns,-1,PREG_SPLIT_NO_EMPTY);
-		foreach($columns as $i=>$col)
+		}
+		
+		foreach ($columns as $i=>$col) {
 			$columns[$i]=$this->db->quoteColumnName($col);
+		}
+		
 		return 'ALTER TABLE ' . $this->db->quoteTableName($table) . ' ADD CONSTRAINT '
 			. $this->db->quoteColumnName($name) . '  PRIMARY KEY ('
 			. implode(', ', $columns). ' )';