Migrating database changes from development to live
I've never come across a tool that would do the job. Instead I've used individual files, numbered so that I know which order to run them: essentially, a manual version of Rails migrations, but without the rollback.
Here's the sort of thing I'm talking about:
000-clean.sql # wipe out everything in the DB001-schema.sql # create the initial DB objects002-fk.sql # apply referential integrity (simple if kept separate)003-reference-pop.sql # populate reference data004-release-pop.sql # populate release data005-add-new-table.sql # modification006-rename-table.sql # another modification...I've never actually run into any problems doing this, but it's not very elegant. It's up to you to track which scripts need to run for a given update (a smarter numbering scheme could help). It also works fine with source control.
Dealing with surrogate key values (from autonumber columns) can be a pain, since the production database will likely have different values than the development DB. So, I try never to reference a literal surrogate key value in any of my modification scripts if at all possible.
I don't trust programmatic migrations. If it's a simple change, such as adding a NULLable column, I'll just add it directly to the live server. If it's more complex or requires data changes, I'll write a pair of SQL migration files and test them against a replica database.
When using migrations, always test the rollback migration. It is your emergency "oh shit" button.
I've used this tool before and it worked perfectly.
It takes as an input either a DB connection or a SQL file, and compares it to the same (either another DB connection or another SQL file). It can spit out the SQL to make the changes or make the changes for you.