We often get posts about switching database types, eg, from MySQL -> Oracle, MySQL – MSSQL, etc.
The following tool helps do that but it is commercial though. I think it is fairly priced also.
Do have a look.I hope this helps.
http://www.swissql.com/products/datamigration/data-migration.html
Disclosure: The SwisSQL product belongs to AdventNet. AdventNet is the angel investor of vtiger.