是否可以按预定顺序执行 SELECT
语句,即.选择 ID 7、2、5、9 和 8 并按该顺序返回,仅基于 ID 字段?
Is it possible to do a SELECT
statement with a predetermined order, ie. selecting IDs 7,2,5,9 and 8 and returning them in that order, based on nothing more than the ID field?
这两个语句都以相同的顺序返回它们:
Both these statements return them in the same order:
SELECT id FROM table WHERE id in (7,2,5,9,8)
SELECT id FROM table WHERE id in (8,2,5,9,7)
我不认为这是可能的,但找到了一个 此处的博客条目 似乎是您所追求的类型:
I didn't think this was possible, but found a blog entry here that seems to do the type of thing you're after:
SELECT id FROM table WHERE id in (7,2,5,9,8)
ORDER BY FIND_IN_SET(id,"7,2,5,9,8");
会给不同的结果
SELECT id FROM table WHERE id in (7,2,5,9,8)
ORDER BY FIND_IN_SET(id,"8,2,5,9,7");
FIND_IN_SET
返回给它的第二个参数中 id
的位置,因此对于上面的第一种情况,7 的 id
在集合中的位置 1, 2 at 2 等等 - mysql 内部计算出类似
FIND_IN_SET
returns the position of id
in the second argument given to it, so for the first case above, id
of 7 is at position 1 in the set, 2 at 2 and so on - mysql internally works out something like
id | FIND_IN_SET
---|-----------
7 | 1
2 | 2
5 | 3
然后根据FIND_IN_SET
的结果进行排序.
then orders by the results of FIND_IN_SET
.
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