Hibernate 公式注解——MySql 函数:INTERVAL、DAY [英] Hibernate Formula Annotation - MySql functions: INTERVAL, DAY

问题描述

我有代码:

@Id
@Column(name = "id")
@GeneratedValue
private int id;

@Formula(value = "(SELECT count(history.city_id) FROM history where history.ts > (now() - INTERVAL 30 DAY) and history.city_id = id)")
private int last30daysUpdates;

所以，hiberante 将这个公式解析为:

so, hiberante parse this formula to:

 ...where
            history.ts > (
                now() - entitycity0_.INTERVAL 30 entitycity0_.DAY
            ) ...

错误是:

您的 SQL 语法有错误；检查与您的 MySQL 服务器版本相对应的手册，了解在 '30 entitycity0_.DAY) 附近使用的正确语法

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '30 entitycity0_.DAY)

我怎么能说休眠了 INTERVAL 和 DAY 是 MysqL 的功能?可能吗?

How can i say hibernate that INTERVAL and DAY are the functions of MysqL? Is it possible?

谢谢.

推荐答案

您使用哪种 MySQL 方言?如果 MySqlDialect 或 MySql5Dialect 你可以使用如下:

Which MySQL dialect are you use? If MySqlDialect oder MySql5Dialect you can use follows:

SELECT count(history.city_id) FROM history where timediff(now(), history.ts) < '720' and history.city_id = id

或者定义新的休眠函数

public class ExtendedMySQL5Dialect extends MySQL5Dialect 
{
        public ExtendedMySQL5Dialect() 
        {
           super();
           registerFunction( "date_sub_interval", new SQLFunctionTemplate( Hibernate.DATE, "date_sub(?1, INTERVAL ?2 ?3)" ) );
           registerFunction( "date_add_interval", new SQLFunctionTemplate( Hibernate.DATE, "date_add(?1, INTERVAL ?2 ?3)" ) );           
        }
}

查询:

History.ts < date_sub_interval(now(), 30, DAY)

这篇关于Hibernate 公式注解——MySql 函数:INTERVAL、DAY的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！