IN子句中的SQL多列转换为JPA [英] SQL Multiple Columns in IN clause to convert to JPA

问题描述

我想将 IN 子句中的多列转换/翻译下面的查询为 JPA 。

I want to convert/translate the below query with multiple columns in IN clause to JPA.

查询：

Query:

SELECT city FROM user WHERE (firstName, lastName) IN (('a', 'b'), ('c', 'd'));

推荐答案

我不知道JPA是什么谷歌它，我的意思是，我不熟悉它）;但是：如果有任何希望处理SQL查询，并且唯一的问题是转换元组上的条件，那么重新编写这样的查询：

I don't know what JPA is (I can Google it; what I mean is that I am not familiar with it); but: if there is any hope to handle a SQL query, and the only issue is translating a condition on tuples, then rewrite the query like so:

select city 
from   user
where  firstname = 'a' and lastname = 'b'
   or  firstname = 'c' and lastname = 'd'
;

这就是查询引擎对原始查询执行的操作。你可以看看一个解释计划来说服你自己。

This is what the query engine will do with your original query regardless; you can look at an EXPLAIN PLAN to convince yourself of this.

有些人喜欢在每对和连接条件;我不会，除了我会用2 * 3 + 4 * 6的圆括号，但如果你觉得他们增加了清晰度，你可以添加它们。

Some people like to put parentheses around each pair of AND-connected conditions; I don't, any more than I would use parentheses for 2 * 3 + 4 * 6, but if you feel they add clarity, by all means you can add them.

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