How to migrate from MySql to HSQLDB? I have large amount of data in a MySQL database. 

There are many databases schemas in the database. 

How I can migrate from MySQL to HSQLDB? 

Is there some tool for this? 

I've exported the data manually.  How can I export only schema.sql?
Take a look at Comparison of database tools, there you find some tools supporting both HSQL
 and MySQL. Then it should be possible to export the MySQL DB and directly import to HSQL DB from the same GUI.