I have two sites. One is test site with Drupal - and after 2-3 months of work time has come to transfer that site to another host. Note that only way to connect to mysql on both sites is through CPanel and phpMyAdmin.
Now I export test Drupal site with all structure and data, and erased INSERT statements for next tables acsesslog, cache, locales_soruce, locales_target, search_index, search_total, session, watchdog (without this export sql file was too big for phpMyAdmin too process). I also changed the prefix of tables - on test site there was no prefix, and on production I added 'dp_' in exported sql script.
And then on production site I import, with a help of phpMyAdmin, modified exported sql file from test Drupal site. Copy all Drupal files and everything is good - all content is there, all users, logging of existing users is working...
But, problem arise when I try to add some new content on production site. For example, I try to register a new user, and Drupal tries to add that user in users table with a uid 1 (and last existing user is uid 17). And I get error
Duplicate entry '1' for key 1 query: INSERT INTO users (...
Because there is allready user with uid 1.
Same is with forum - when I add new forum topic, Drupal start from nid 1 in node table, but there is allready node with nid 1.
I experiment with auto_increment mysql command in exportet sql script but that failed.