Mysql – Sharing the MySQL databases between two servers

If your end goal is to separate the servers then I would suggest running a separate instance on a different port and using standard replicaton between the two

quick google turns out this

alternatively you can use triggers to replicate, something along the lines of

CREATE TRIGGER replicatetable AFTER INSERT ON db1.table
  FOR EACH ROW BEGIN
    INSERT INTO db2.table(field1,field2, ...) values (db1.table.field1,db1.table.field2, ...);
  END;

similar for UPDATE and DELETE

This is not about replication - just use an additional table:

CREATE TABLE car_more (
    carId INT NOT NULL,
    make INT,
    workHistory
    PRIMARY KEY (carId)
);

If the databases you refer to (do you mean databases or tables?) are on seperate instance of mysql, then use the federated engine to provide remote access to the existing table. Then you can access the data using....

SELECT a.carId, a.name, a.model, b.make, b.workHistory
FROM car a
LEFT JOIN car_more b
ON (a.carId=b.carId);

If they are on the same mysq instance, then just prefix the table names with database names:

SELECT a.carId, a.name, a.model, b.make, b.workHistory
FROM maindb.car a
LEFT JOIN alternatedb.car_more b
ON (a.carId=b.carId);

(you could use mysql amster-master replication to maintain a local copy of the car table - but this is a lot more complicated)