1) Please read the documentation/help file about the Schema Designer in SQLyog:
“Whatever you add or change from the Schema Designer will be stored to the database exactly the same way as when you work with the menu's of the program. There is no need to 'upload', 'apply', 'synchronize' the LAYOUT or anything like that. SQLyog Schema Designer is a graphical implementation of direct client functionalities. We work with the database that we are connected to – not with any kind of 'model' internal for the program (but note that if you want a 'model' before applying the changes to the 'real' or 'live' database you can simply use another database as a 'model' – and use Schema Synchronisation to synchronise from the 'model database' to the 'real database'. The two databases need not be on the same server).”
2) “persistent graphical models that it can be loaded/refreshed from the database”. With the above limitation that is possible. There is a refresh option. But we do not support building a LAYOUT (the term we use to distinguise it from a MODEL) from SQL – only from our own XML format. Also the Schema Designer is restricted to handling tables – not 'stored programs' of any kind.
We know that the Schema Designer is not a full featured ERD diagramming tool. It was never the intention either. The Schema Designer is just a 'small corner' of SQLyog and a full featured ERD diagramming tool would be priced several times the pricing of SQLyog. We have no plans of building such whether as a seperate application or as a part of SQLyog.
