sql - 查询时保留顺序

Question

我有这个查询，我想保留顺序

SELECT a FROM TABLE WHERE id in (2,45, 87, 10,12, 41, 29)

现在我想要按这个顺序的a值，我的意思是a for 2，然后是a for 45，然后是a for 87。我如何在sql中完成这个

Answer 1

在 MySQL 中，您可以使用 ORDER BY FIELD :

SELECT a
FROM yourtable
WHERE id IN (2, 45, 87, 10, 12, 41, 29)
ORDER BY FIELD (id, 2, 45, 87, 10, 12, 41, 29)

在不支持 FIELD 的数据库中，您可以改用 CASE 表达式:

SELECT a
FROM yourtable
WHERE id IN (2, 45, 87, 10, 12, 41, 29)
ORDER BY CASE
    WHEN id = 2 THEN 1
    WHEN id = 45 THEN 2
    WHEN id = 87 THEN 3
    WHEN id = 10 THEN 4
    WHEN id = 12 THEN 5
    WHEN id = 41 THEN 6
    WHEN id = 29 THEN 7
END