A few solutions exist to migrate contacts and data you can look at. It depends on the type of software you want to use. You can look into software such as Informatica or Talend Open Studio, an open source program.
You could work with proprietary software that can be expensive compared to solutions such as open source.
What do you men the migration should be done manually? From where you need to transfer data from?
if your source is SQL server, you can write triggers to transfer data to mysql, so when ever any edit,delete ,insert happens in SQL , you will going to see in mysql.