Every company makes a different decision about the database to use when they start. However, as soon as they move forward and their decisions mature, which, of course is based on the best interest of the organization. Many organizations make different decisions on database like MySQL, Oracle, Access and as the time pass by, they learn that they want to make a move on a different platform.
So hre are the different tools to help you with that:
SQL Server Migration Assistant is a free supported tool from Microsoft that simplifies the database migration process from Sybase Adaptive Server Enterprise to SQL Server and Azure SQL DB, SSMA automates and all aspects of migration including migration assessment analysis, schema, and SQL statement conversion, as well as migration testing.
Read the rest of the tools here: http://blog.sqlauthority.com/2014/08/09/sql-server-microsoft-sql-server-migration-assistant-v6-0-released/