更新InnoDB表中的auto_increment值

Question

Short version: Can I programatically update the auto_increment value on a table? I'm trying to do this via the mysql init_file so it happens on startup, but I don't see it working.

USE theDb;

SELECT max(maxid) FROM (SELECT max(RegistrationId)+1 maxid FROM Registration
UNION
SELECT max(RegistrationId)+1 maxid FROM RegistrationArchive) t into @maxId;

ALTER TABLE Registration AUTO_INCREMENT=@maxId;

Longer version: I have a mysql database with InnoDB tables. One table (holding registration info) has an auto increment column and when a row is processed, it is copied to a second archive table and is deleted from the first. The archive table does not have an auto increment column. (btw, not my design...)

Problem is that when the database is restarted for some reason, which is infrequent, the first table recalulates the next increment value -- a feature of InnoDB. The table will often be empty or very small and the calculated next increment will correspond to an id that has already been used and is in the archive table. The data gets moved to archive ok, but subsequent processes don't work right after that.

Answer 1

I know this is a late, but after asking this related question , I found out that certain parts of an sql statement need to be literals and can't be replaced by user_defined_variables. If you need to change such parts of an SQL statement you need to use prepared statements .

So you need to do something like this:

SET @`stmt_alter` := CONCAT('ALTER TABLE `Registration` AUTO_INCREMENT = ', @`maxId`);
PREPARE `stmt` FROM @`stmt_alter`;
EXECUTE `stmt`;
DEALLOCATE PREPARE `stmt`;