修正Query类的builder方法

library/think/Model.php

@@ -853,10 +853,11 @@ abstract class Model implements \JsonSerializable, \ArrayAccess
 
         if (!isset(self::$links[$model])) {
             self::$links[$model] = Db::connect(static::$connection);
-        }
             self::$links[$model]->setTable(static::$tableName);
             $name = basename(str_replace('\\', '/', $model));
             self::$links[$model]->name($name);
+        }
+
         // 设置当前模型 确保查询返回模型对象
         self::$links[$model]->model($model);
         // 返回当前数据库对象

library/think/db/Builder.php

@@ -38,9 +38,19 @@ abstract class Builder
      * @access public
      * @param object $db 数据库对象实例
      */
-    public function __construct($connection, $query)
+    public function __construct($connection)
     {
         $this->connection = $connection;
+    }
+
+    /**
+     * 设置当前的Query对象实例
+     * @access protected
+     * @param \think\db\Query $query 当前查询对象实例
+     * @return void
+     */
+    public function setQuery($query)
+    {
         $this->query = $query;
     }
 

library/think/db/Query.php

@@ -77,8 +77,10 @@ class Query
         $driver         = $this->driver;
         if (!isset($builder[$driver])) {
             $class            = '\\think\\db\\builder\\' . ucfirst($driver);
-            $builder[$driver] = new $class($this->connection, $this);
+            $builder[$driver] = new $class($this->connection);
         }
+        // 设置当前查询对象
+        $builder[$driver]->setQuery($this);
         return $builder[$driver];
     }