Question

I have an auto generated timestamp that is created each time a record is inserted or updated in a mysql table. Is there a way to return this timestamp in a way similar to how I would use a keyholder to return a newly created id?

KeyHolder keyHolder = new GeneratedKeyHolder();
JdbcTemplate jdbcTemplate = new JdbcTemplate(dataSource);

//Insert Contact
jdbcTemplate.update(new PreparedStatementCreator() {
    @Override
    public PreparedStatement createPreparedStatement(Connection connection) throws SQLException {
        PreparedStatement preparedStatement = connection.prepareStatement(SQL_ADD, Statement.RETURN_GENERATED_KEYS);
        preparedStatement.setString(1, contact.getFirstName());
        preparedStatement.setString(2, contact.getLastName());
        preparedStatement.setInt(3, contact.getOrganizationId());
        preparedStatement.setString(4, contact.getType());
        preparedStatement.setInt(5, contact.getUserId());
        return preparedStatement;
        }   
}, keyHolder);
//Use keyholder to obtain newly created id
contact.setId(keyHolder.getKey().intValue());

Is there some way to also return the new timestamp without having to requery the table? I have been looking for ways to return it along with the id as a key in the keyholder, but it doesn’t seem to be returned as a key?

Answer 1

There are few options for solving this issue on the MySQL database server side. You could start with creating a TRIGGER on the table. As TRIGGER has a restriction and cannot return data, you can set the TIMESTAMP value to a variable:

DEMILITER //
CREATE TRIGGER ai_tbl_name AFTER INSERT ON tbl_name
FOR EACH ROW
BEGIN

SET @TimeStamp = NEW.timestamp_column;

END;//
DELIMITER ;

To retrieve this timestamp value, run the following command:

SELECT @TimeStamp;

Since the variables are stored in the memory, there will be no need to open any tables again.

You go even further. You could create a STORED PROCEDURE in MySQL to automate all the above (sample code, as I do not know your table’s details):

DELIMITER //
DROP PROCEDURE IF EXISTS sp_procedure_name //
CREATE PROCEDURE sp_procedure_name (IN col1_val VARCHAR(25),
                                    IN col2_val VARCHAR(25),
                                    IN col3_val INT)
BEGIN
    INSERT INTO tbl_name (col1, col2, col3)
    VALUES (col1_val, col2_val, col3_val);

    SELECT @TimeStamp;
END; //
DELIMITER ;

You can run this procedure with the following code:

CALL sp_procedure_name(col1_val, col2_val, col3_val);

As I’m not familiar with the Java, you’ll need to finish it up with your side of code.