I have a MySQL table that I deleted a large amount of records from. Then all new records are inserted with the AUTO_INCREMENT still assuming the table had all those records in it. Fortunately you can reset the internal AUTO_INCREMENT count for a given table:
ALTER TABLE TableName AUTO_INCREMENT = 987;
This will set the AUTO_INCREMENT counter to 987. Thus all records inserted after that will start at 988. Unless there are records with a higher value than the auto_increment, then it will use that higher value + 1. Pretty handy.