如何查询“超过三分钟”在JPA？ [英] How do I query "older than three minutes" in JPA?

问题描述

有没有办法在JPA查询中引用当前时间的日期范围条件（跨数据库兼容）？

Is there a way to put a date range condition referencing the current time in a JPA query (that is compatible across databases)?

我可以做

SELECT m FROM Mail m WHERE m.sentAt < :date

但是我想做，而不必绑定一个参数（这样可以配置作为命名查询库的一部分，日期计算逻辑不必输入调用代码）。

but I want to do it without having to bind a parameter (so that this can be configured as part of the named query repository and the date calculation logic does not have to enter the calling code).

所以而不是：date 我需要currentTime减3分钟作为硬码文字。

So instead of :date I need "currentTime minus 3 minutes" as a hard-code literal.

推荐答案

JPA支持CURRENT_TIMESTAMP和CURRENT_TIME函数。

JPA supports the CURRENT_TIMESTAMP and CURRENT_TIME functions.

https：/ /en.wikibooks.org/wiki/Java_Persistence/JPQL#Functions

JPA规范没有日期功能，但是一些JPA提供程序（如EclipseLink） 。

The JPA spec does not have date functions, but some JPA providers such as EclipseLink do.

http://java-persistence-performance.blogspot.com/2012/05/jpql-vs-sql-have-both-with-eclipselink.html

JPA 2.1还定义了调用数据库函数的FUNCTION运算符。

JPA 2.1 also defines the FUNCTION operator to call database functions.

在EclipseLink中，我会尝试，

In EclipseLink I would try,

SELECT m FROM Mail m WHERE m.sentAt < SQL("(sysdate - interval '3' minute)")

或

SELECT m FROM Mail m WHERE m.sentAt < SQL("(? - interval '3' minute)", CURRENT_TIMESTAMP)

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