How can I tell when a MySQL table was last updated?

In later versions of MySQL you can use the information_schema database to tell you when another table was updated:

SELECT UPDATE_TIME
FROM   information_schema.tables
WHERE  TABLE_SCHEMA = 'dbname'
   AND TABLE_NAME = 'tabname'

This does of course mean opening a connection to the database.

An alternative option would be to "touch" a particular file whenever the MySQL table is updated:

On database updates:

• Open your timestamp file in O_RDRW mode
• close it again

or alternatively

• use touch(), the PHP equivalent of the utimes() function, to change the file timestamp.

On page display:

• use stat() to read back the file modification time.

Although there is an accepted answer I don't feel that it is the right one. It is the simplest way to achieve what is needed, but even if already enabled in InnoDB (actually docs tell you that you still should get NULL ...), if you read MySQL docs, even in current version (8.0) using UPDATE_TIME is not the right option, because:

Timestamps are not persisted when the server is restarted or when the table is evicted from the InnoDB data dictionary cache.

If I understand correctly (can't verify it on a server right now), timestamp gets reset after server restart.

As for real (and, well, costly) solutions, you have Bill Karwin's solution with CURRENT_TIMESTAMP and I'd like to propose a different one, that is based on triggers (I'm using that one).

You start by creating a separate table (or maybe you have some other table that can be used for this purpose) which will work like a storage for global variables (here timestamps). You need to store two fields - table name (or whatever value you'd like to keep here as table id) and timestamp. After you have it, you should initialize it with this table id + starting date (NOW() is a good choice :) ).

Now, you move to tables you want to observe and add triggers AFTER INSERT/UPDATE/DELETE with this or similar procedure:

CREATE PROCEDURE `timestamp_update` ()
BEGIN
    UPDATE `SCHEMA_NAME`.`TIMESTAMPS_TABLE_NAME`
    SET `timestamp_column`=DATE_FORMAT(NOW(), '%Y-%m-%d %T')
    WHERE `table_name_column`='TABLE_NAME';
END

OS level analysis:

Find where the DB is stored on disk:

grep datadir /etc/my.cnf
datadir=/var/lib/mysql

Check for most recent modifications

cd /var/lib/mysql/{db_name}
ls -lrt

Should work on all database types.

I got this to work locally, but not on my shared host for my public website (rights issue I think).

SELECT last_update FROM mysql.innodb_table_stats WHERE table_name = 'yourTblName';

'2020-10-09 08:25:10'

MySQL 5.7.20-log on Win 8.1

a) It will show you all tables and there last update dates

SHOW TABLE STATUS FROM db_name;

then, you can further ask for specific table:

SHOW TABLE STATUS FROM db_name like 'table_name';

b) As in above examples you cannot use sorting on 'Update_time' but using SELECT you can:

SELECT * FROM information_schema.tables WHERE TABLE_SCHEMA='db_name' ORDER BY UPDATE_TIME DESC;

to further ask about particular table:

SELECT * FROM information_schema.tables WHERE TABLE_SCHEMA='db_name' AND table_name='table_name' ORDER BY UPDATE_TIME DESC';

i made a column by name : update-at in phpMyAdmin and got the current time from Date() method in my code (nodejs) . with every change in table this column hold the time of changes.

Same as others, but with some conditions i've used, to save time:

SELECT
  UPDATE_TIME,
  TABLE_SCHEMA,
  TABLE_NAME
FROM
  information_schema.tables
WHERE
  1 = 1
  AND UPDATE_TIME > '2021-11-09 00:00:00'
  AND TABLE_SCHEMA = 'db_name_here'
  AND TABLE_NAME not in ('table_name_here',)
ORDER BY
  UPDATE_TIME DESC,
  TABLE_SCHEMA,
  TABLE_NAME;

Cache the query in a global variable when it is not available.

Create a webpage to force the cache to be reloaded when you update it.

Add a call to the reloading page into your deployment scripts.