SQL：通过ROWID，然后通过基于ROWID列顺序

Question

我有以下'departments'表：

+-------+-------------+-------------------+ 
| rowid | department | parent_department | 
+-------+-------------+-------------------+ 
| 10 | Main Office | NULL    | 
+-------+-------------+-------------------+ 
| 11 | Back Office | 10    | 
+-------+-------------+-------------------+ 
| 12 | Commercial | NULL    | 
+-------+-------------+-------------------+ 
| 13 | Outdoor  | NULL    | 
+-------+-------------+-------------------+ 
| 14 | Beach  | 13    | 
+-------+-------------+-------------------+ 
| 15 | Gardening | 13    | 
+-------+-------------+-------------------+ 
| 16 | Accounting | 10    | 
+-------+-------------+-------------------+ 

，我想它基于ROWID和parent_department因此下令：

+-------+-------------+-------------------+ 
| rowid | department | parent_department | 
+-------+-------------+-------------------+ 
| 10 | Main Office | NULL    | 
+-------+-------------+-------------------+ 
| 11 | Back Office | 10    | 
+-------+-------------+-------------------+ 
| 16 | Accounting | 10    | 
+-------+-------------+-------------------+ 
| 13 | Outdoor  | NULL    | 
+-------+-------------+-------------------+ 
| 14 | Beach  | 13    | 
+-------+-------------+-------------------+ 
| 15 | Gardening | 13    | 
+-------+-------------+-------------------+ 
| 12 | Commercial | NULL    | 
+-------+-------------+-------------------+ 

因此，对于每个rowid，查找是否存在'parents_departments'并按如下所示显示顺序。

请注意，我没有设计当前表，可悲的是我没有去改变它

Answer 1

试试这个权限：

SELECT rowid, department, parent_department 
    FROM departments 
ORDER BY IFNULL(parent_department, rowid), rowid;