mysql需要获取结果的自定义顺序

Question

有像id ， parent_id ， order_nr这样的MySQL表

现在选择这样的一切

SELECT * FROM `table1` WHERE 1 ORDER BY `id` DESC

并得到像

`id`, `parent_id`, `order_nr`
"27",   "23",       "3" 
"26",   "23",       "2" 
"25",   "23",       "1" 
"24",   "0",        "0" 
"23",   "0",        "0" 
"22",   "0",        "0" 

只需按以下顺序获得相同的结果：

`id`, `parent_id`, `order_nr`
"24",   "0",        "0" 
"23",   "0",        "0" 
"25",   "23",       "3" 
"26",   "23",       "2" 
"27",   "23",       "1"
"22",   "0",        "0" 

Answer 1

这个怎么样：

SELECT * FROM `table1` WHERE 1 ORDER BY order_nr,parent_id,id DESC

您可以尝试交换应该先订购的列。

Answer 2

假设parent_id和order_nr是varchar列，但是您想将它们按数字排序，那么可以在订购时order_nr这些列：

SELECT *
FROM table1
ORDER BY CAST(parent_id AS SIGNED),   -- no need for CAST if already numeric
         CAST(order_nr AS SIGNED)

注意：您期望的第一个输出似乎没有任何明显的逻辑，因此我为第二个给出了解决方案。

Answer 3

SELECT * FROM `table1` WHERE 1 ORDER BY `parent_id`, `order_nr` ASC

输出如下：

`id`, `parent_id`, `order_nr`
"24",   "0",        "0" 
"23",   "0",        "0" 
"22",   "0",        "0" 
"25",   "22",       "1" 
"26",   "22",       "2" 
"27",   "22",       "3" 

Answer 4

假设ID为两位数（但可以扩展为任意位数）

SELECT IF(parent_id=0,id,parent_id)*100+IF(parent_id=0,0,id)),* FROM table ORDER BY 1 DESC

或者id是字符串

SELECT CONCAT(IF(parent_id='0',LPAD(id,2,'0'),LPAD(parent_id,2,'0')),IF(parent_id='0','00',LPAD(id,2,'0'))),* FROM table ORDER BY 1 DESC

这将为您提供第一列，即

2400 2300 2227 2226 2225 2200

Answer 5

当parent_id为0时，只需使用id否则使用parent_id ； 然后按order_nr排序打破order_nr 。 所有排序都是降序排列：

SELECT id, parent_id, order_nr,
       id AS sort_order
  FROM table1
 WHERE parent_id = '0'
UNION
SELECT id, parent_id, order_nr,
       parent_id AS sort_order
  FROM table1
 WHERE parent_id <> '0'
 ORDER
    BY sort_order DESC, order_nr DESC;