在Java中以毫秒精度将Instant datetime插入MySql数据库

Question

I am using mysql 5.7.x version. Also i am using java 8. I am trying to insert java.time.instant current datetime in millisecond precision into my mysql database from java code. For that I am using preparedstatement .

The table in my database is:

CREATE TABLE `test_table` (
`id` INT NOT NULL AUTO_INCREMENT,
`timestamp` TIMESTAMP(3) NOT NULL,
PRIMARY KEY (`id`));

My java code to insert is:

    Instant instant = Instant.now().truncatedTo(ChronoUnit.MILLIS);

    try (Connection conn = DbConnection.getCon();
            PreparedStatement ps = conn.prepareStatement("INSERT INTO test_table (timestamp) VALUES (?)");) {
        ps.setTimestamp(1, Timestamp.from(instant));
        ps.executeUpdate();
        LOG.info("Instant: {} and long: {}", instant, instant.toEpochMilli());
    } catch (SQLException ex) {
        LOG.error(ex.getMessage());
    }

From my log, I can see instant with milliesecond as: 2019-07-30T10:52:34.865Z. But in my mysql database it becomes: 2019-07-30 10:52:34.000Z

I have searched so many questions and answers in stack but none seems to work for me.

Update 1:

I tried using setObject as:

ps.setObject(1, Timestamp.from(instant));

But still same result. Cannot retrieve the milliseconds in database.

Answer 1

MySQL has FROM_UNIXTIME() function that can take long values inside and returns a representation of the unix_timestamp in 'YYYY-MM-DD hh:mm:ss' or 'YYYYMMDDhhmmss.uuuuuu' format. Reference from their manual here: FROM_UNIXTIME()

Since I have milliseconds since epoch, thus I have to use

FROM_UNIXTIME(instant.toEpochMilli() * 0.001)

in my insert statement.

Yes nothing needs to be changed in database. The only things that are changed are in java code which are setObject() function used for preparedStatement , passing instant.toEpochMilli() as the argument there and finally use of FROM_UNIXTIME() function inside insert statement.

My final java code looks something like this:

Instant instant = Instant.now().truncatedTo(ChronoUnit.MILLIS);

    try (Connection conn = DbConnection.getCon();
            PreparedStatement ps = conn.prepareStatement("INSERT INTO test_table (timestamp) VALUES (FROM_UNIXTIME(?*0.001))");) {
        ps.setObject(1, instant.toEpochMilli());
        ps.executeUpdate();
        LOG.info("Instant: {} and long: {}", instant, instant.toEpochMilli());
    } catch (SQLException ex) {
        LOG.error(ex.getMessage());
    }