I have a single drupal 4.7.4 installation running (win2k server) about 35 sub-sites. I used to have 35 different mysql databases but to make the DBs more manageable, I combined all the databases into a single one, adding prefixes to all table names, and made appropriate changes in the settings.php files.
It seemed to work all dandy until I tried to add any content/user/anything to any of the sites. My big database is called 'clubs' and wildlife is one of the subsites with a table prefix of 'wildlife_'. When I try to add a new page, this is the error I get:
user warning: Duplicate entry '9-9' for key 1 query: INSERT INTO wildlife_node (nid, vid, title, type, uid, status, created, changed, comment, promote, moderate, sticky) VALUES (9, 9, 'gdsfgdsf', 'page', 1, 1, 1163177001, 1163177001, 2, 1, 0, 0) in C:\xampp\xampp\htdocs\clubs\includes\database.mysql.inc on line 121.
user warning: Duplicate entry '9' for key 1 query: INSERT INTO wildlife_node_revisions (nid, vid, title, body, teaser, log, timestamp, uid, format) VALUES (9, 9, 'gdsfgdsf', 'gdsfgsdfg', 'gdsfgsdfg', '', 1163177001, 1, 1) in C:\xampp\xampp\htdocs\clubs\includes\database.mysql.inc on line 121.
user warning: Duplicate entry '9' for key 1 query: INSERT INTO wildlife_node_comment_statistics (nid, last_comment_timestamp, last_comment_name, last_comment_uid, comment_count) VALUES (9, 1163177001, NULL, 1, 0) in C:\xampp\xampp\htdocs\clubs\includes\database.mysql.inc on line 121.