Update all DATETIME fields in the database

Question

I'm currently storing all DATETIME fields in my database in US Eastern time, and would like to UPDATE them all to UTC. I have a lot of DATETIME fields in lots of different tables. Is there a way to identify and UPDATE them all at once?

Answer 1

You could generate the UPDATE statements that you need with following statements:

SET @tzdiff = 5;    -- difference between EST and UTC
SET @db = 'test4';  -- your DB name
SELECT
    CONCAT(
        'UPDATE ',
        '`', c.TABLE_NAME, '` ', 
        'SET ', 
        '`', COLUMN_NAME, '` = ',
        '`', COLUMN_NAME, '` + INTERVAL ', @tzdiff, ' HOUR;' 
    ) as update_statement
FROM
    INFORMATION_SCHEMA.COLUMNS c
WHERE
    c.TABLE_SCHEMA = @db
AND
    c.`DATA_TYPE` LIKE 'datetime';

Result for my database 'test4':

update_statement
-----------------------------------------------------------------------
UPDATE `example12` SET `column_name` = `column_name` + INTERVAL 5 HOUR;
UPDATE `post` SET `expiration` = `expiration` + INTERVAL 5 HOUR;

For a one-time-job, I would simply copy the result into the MySQL client of your choice and execute them. Of course it's possible to create prepared statements for the results and execute them.