Thank you for your post into the forum.
Before you update and make changes to the website database, I recommend that you backup this database and then restore a copy of it to a test machine.
Next compare the database on your local computer with the copy of the website database on the test machine. Followed by syncronization and observe what occurs.
When you perform the comparison you will be informed of the following:
Objects that exist only in the local computer.
Objects that exist in both data sources but are different.
Objects that exist only in the Website database.
Objects that are identical.
When you synchronize (in the direction of local database to website database) by default, dependent upon the object you have included in the synchronization, SQL Compare will:
1. Objects that exist only in the local computer, will be created in the website database. This will incur no data loss as new objects are being created.
2. Objects that exist in both data sources but are different, the objects in the website database will be altered to match the local database. This may incur data loss, as existing table columns may be dropped or deleted and the data held in these columns will be lost.
3. Objects that exist only in the Website database, these objects will be dropped. This will result in data loss.
When you review the comparison results only select the individual objects you wish to synchronize.
But I can only stress that you should test before moving to your live website database. Also backup the live website database immediatley before synchronizing the database, this will allow you to recover back / restore to the same database state before you run the synchronization process.