What is the best way to rebuild a model without loss data in MySQL for Symfony?
What if I have a big site, and a lot of data in the database and I would like after six months to add few new fields to database?
You can use migration.
So you need write migrations, migrate, and build your models, forms, etc.
I suggest you use @denys281 for Symfony1.4 ....in Symfony2 however its VERY simple ... just use the command :
php app/console doctrine:schema:update --force
It compares what your database should look like (based on the mapping information of your entities) with how it actually looks, and generates the SQL statements needed to update the database to where it should be. In other words, if you add a new property with mapping metadata to Product and run this task again, it will generate the "alter table" statement needed to add that new column to the existing product table. So it doesnt remove any data
There is also a DoctrineMigrations bundle for Symfony2 if you fancy that route -> http://symfony.com/doc/current/bundles/DoctrineMigrationsBundle/index.html
来源：https://stackoverflow.com/questions/8138667/rebuild-model-without-loss-data-in-mysql-for-symfony