mysql两列主键自动递增

I have multiple databases with the same structure in which data is sometimes copied across. In order to maintain data integrity I am using two columns as the primary key. One is a database id, which links to a table with info about each database. The other is a table key. It is not unique because it may have multiple rows with this value being the same, but different values in the database_id column. I have multiple databases with the same structu