Use Triggers : The MySQL trigger is a database object that is associated with a table. It will be activated when a defined action is executed for the table.
The trigger can be executed when you run one of the following MySQL statements on the table: INSERT, UPDATE and DELETE and it can be invoked before or after the event.
You can make trigger when you insert or update a row in main table and make the changes in another table
Example:
DELIMITER $$
CREATE TRIGGER my_sync_trigger
AFTER INSERT ON `clients` for each row
begin
INSERT INTO calender (id,client)
Values (new.id, new.client);
END$$
DELIMITER ;
"new" stands for the new value inserted into clients table. The same value will be inserted into id and client column in calender.
Note: single quotes are removed from table name because quotes effectively make it a string literal instead of a proper identifier.
DELIMITER command will change the ending of each statement from ";" to "$$" so that MySQL is not confused with ";" inside and outside the trigger
Make similar triggers for update and delete also
Simple guide for examples and syntax:
http://www.mysqltutorial.org/create-the-first-trigger-in-mysql.aspx