How to copy selected table data from sql server to mysql on a daily basis?
You have a few options:


Set up a linked servers on SQL Server against the MySQL db, and then join the data as needed on the SQL Server side
Having set up the linked server, you can also copy the table over to a new location using standard SQL (or create a table in MySQL and copy data in).
You can also use Data Transformation Services in SQL Server to export into a csv or similar, to import in MySQL using a csv import tool.


Which one is best depends to some extent on size of the record set and how much of it you need. My preference would be to use DTS and go from there.

Source