使用 Rails AREL 的复杂订单语句：SQL Case 语句
我有这段代码，基本上尝试在活动关系顺序方法中使用 SQL case 语句：
relation = Foo.order("CASE WHEN foos.thing IS NOT NULL THEN 0 ELSE 1 END ASC")
在生成（和执行）的 SQL 中，它显示为：
(ORDER BY CASE ASC)
我尝试深入挖掘源代码并丢失在 Visitor.access 调用中线程向下。这是一个已知问题吗？是用户错误吗？我必须做一些神奇的事情才能让它发生吗？我的印象是它只是插入了原始 SQL。我们还对关系执行其他操作，例如选择、限制、偏移、分组、拥有和连接。
帮助！ :)
I've got this bit of code that basically tries to use a SQL case statement in the active relation order method:
relation = Foo.order("CASE WHEN foos.thing IS NOT NULL THEN 0 ELSE 1 END ASC")
and in the generated (and executed) SQL it comes up as:
(ORDER BY CASE ASC)
I've tried digging down into the source and lose the thread down in the visitor.access call. Is this a known issue? Is it user error? Is there some magical thing I have to do to make it happen? I was under the impression that it just inserted the raw SQL. There are other things we're doing with the relation, such as select, limit, offset, group, having and joins.
help! :)
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我也遇到过这个问题：
您可以将 CASE 放入 SELECT 中并命名它，以便您可以在 ORDER BY 中使用它。
I've had this problem too:
You can put the CASE into the SELECT and name it so you can use it in the ORDER BY.