Question

我有以下代码来获取要呈现给用户的项目：

SELECT * FROM main_cue WHERE group_id IN (1,2,3,4) GROUP BY group_id;
>>> 1,2,3,4

但是，我想为此提供一个特定的顺序，这样（1）我有一个要推送到堆栈末尾的项目列表按照我指定的确切顺序和（2））不在列表中的项目将由id ASC订购。例如：

items_to_push_to_end_of_stack_in_this_exact_order = [3,2]

新的排序将是：

>>> [1,4,3,2]
1) 1 # first item by ID asc, not in `items_to_push_to_end_of_stack_in_this_exact_order`
2) 4 # second item by ID asc, not in `items_to_push_to_end_of_stack_in_this_exact_order`
3) 3 # items_to_push_to_end_of_stack_in_this_exact_order
4) 2 # items_to_push_to_end_of_stack_in_this_exact_order

我如何在mysql中执行此操作？

Answer 1

如果您尝试指定排序，请使用order by：

ORDER BY

    // First, Put "2" and "3" at the end of the stack
   (group_id IN (2, 3)) ASC,

   // Second, order the items not in the list by the `group_id`
   (CASE WHEN group_id NOT IN (2, 3) THEN group_id END) ASC,

   // Third, order the items in the list by the ordering you specify
   FIELD(group_id, 3, 2)

这有点复杂。第一个条款将＆＃34; 2＆＃34;和＆＃34; 3＆＃34;在末尾。第二个按group_id排序其余部分。第三个按照您指定的顺序对最后一个订单进行排序。

Answer 2

使用戈登的答案和我目前的代码，这是有效的：

passed_on_group_ids_as_str = ','.join(passed_on_group_ids) # convert the list to csv

cues_per_group = Cue.objects.raw('''SELECT * FROM main_cue WHERE group_id IN %s GROUP BY group_id 
                                        ORDER BY (group_id IN (%s)) ASC,
                                        (CASE WHEN group_id NOT IN (%s) THEN group_id END) ASC,
                                        FIELD(group_id, %s)''', 
                                    (group_ids, passed_on_group_ids_as_str, passed_on_group_ids_as_str, passed_on_group_ids_as_str))

将物品推到堆栈末端（第2部分）

2 个答案: