h2中的CURRENT_TIMESTAMP(以毫秒为单位) [英] CURRENT_TIMESTAMP in milliseconds in h2

问题描述

问题 CURRENT_TIMESTAMP以毫秒为单位讨论了如何从时间戳中减去毫秒MySql或PostgreSql".但是答案中的方法不起作用，因为H2不支持像conv这样的MySQL方法.

The question CURRENT_TIMESTAMP in milliseconds discussed how to "get milliseconds out of a timestamp in MySql or PostgreSql". But the methods in the answers don't work because H2 doesn't support MySQL methods like conv.

我要对架构文件的defaultValueComputed使用CURRENT_TIMESTAMP的变体.

I want to use a variant of CURRENT_TIMESTAMP for the defaultValueComputed of my schema file.

如何获取H2中时间戳的确切毫秒数?我希望它是long.我还希望返回的毫秒数在 Unix时间中.

How can I get the exact milliseconds of a timestamp in H2? I want it be a long. I also want the milliseconds returned to be in Unix time.

这里是我的模式文件中:

Here it is in my schema file:

<column name="create_time" type="long" defaultValueComputed="?"
    <constraints nullable="false"/>
</column>

我有这个DAO对象:

public interface MyDao extends Transactional<MyDao> {
    @SqlUpdate(
        "INSERT INTO my_table "(id, create_time)" +
        "VALUES (:id, :create_time)"
    void insert(@BindBean MyObject myObject);
}

我查看了 http://www.h2database的时间和日期函数"部分.com/html/functions.html ，尽管PARSEDATETIME可能可以工作，但找不到任何可以做到这一点的东西.

I looked at the "Time and Date Functions" section of http://www.h2database.com/html/functions.html and couldn't find anything that could do this though maybe PARSEDATETIME somehow could work.

也许别名是可能的.参见groups.google.com/forum/#！topic/h2-database/kziTTTNlB9o:

Maybe an alias is possible. See groups.google.com/forum/#!topic/h2-database/kziTTTNlB9o:

我要将最初为MySQL编写的应用程序移植到H2 (查询包含一些特定于MySQL的语法).可能是最 使查询在H2上运行具有挑战性的部分是使用 MySQL日期函数，例如DATE()，UNIX_TIMESTAMP()和 FROM_UNIXTIME().好消息是:因为H2支持创建 这些的别名，我能够编写一个很小的Java类， 实现针对H2的这些MySQL函数，一旦我将它们别名为 在这里，H2几乎无需修改即可运行我们所有的查询.

I'm porting an application to H2 that was initially written for MySQL (the queries contain some MySQL-specific syntax). Probably the most challenging part of getting the queries running on H2 has been the use of the MySQL date functions like DATE(), UNIX_TIMESTAMP(), and FROM_UNIXTIME(). The good news is: because H2 supports creating aliases for these, I was able to write a very small Java class that implements these MySQL functions for H2, and once I aliased them into place, H2 runs just about all of our queries without modification.

推荐答案

我知道这是个老问题，但像我这样的人可以作为该问题的搜索答案.我们可以使用h2 DATEDIFF()函数以毫秒为单位获取当前时间.

I know this is old question but anyone like me, can be search answer for this question. We can get current time by millisecond with h2 DATEDIFF() function.

首先，我们传递current_timestamp和第一个日期值，并返回类型SECOND作为参数，例如: DATEDIFF('SECOND', DATE '1970-01-01', CURRENT_TIMESTAMP()) * 1000返回的结果对我们来说是current_time的毫秒.

Fisrtly we pass current_timestamp and first date value and return type SECOND as a parameters like : DATEDIFF('SECOND', DATE '1970-01-01', CURRENT_TIMESTAMP()) * 1000 the returned result is current_time's millisecond for us.

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