I work at a young business with an accounting C# application. This application stores and is fed huge amounts of data from a MySQL database, which has been running for at least a year and a half.
After getting many problems related to how to database was stuctured we decided to make a new database design taking into account all normalization standards. Many tables where merged into a single one and other tables where split into multiple.
Finally we decided on all the structure for our new database and are working on a new design for our C# app to interact with it. We created the new structure using MySQL Workbench.
Problem is we must first work on a solution to migrate all the data from the old stucture to the new one. We're dealing with around 200 Megabytes of data and we have around 3 months to release the new software version.
I know this isn't a simple question that could be answered by one person. What I'm looking for is advice on the topic. Should I write a custom script/application to do all the migration? In what language should I program the migration solution? We want this migration to happen as swiftly as possible so the system is down for a small amount of time.