![dbschema ways to write dbschema ways to write](https://static.macupdate.com/screenshots/287636/m/dbschema-screenshot.png)
In some cases, you'll want to use software like Flyway or Liquibase that just acts as a source control for your database. Option 2: Use Independent Database-Migration-Focused Software Other than that, the library chosen within the framework/language pretty much takes care of this for you.
Dbschema ways to write how to#
Typically in this scenario, you generate the migration files using the command line. Occasionally, you may need to handwrite the custom code for some changes, such as data migration or even how to reverse the change itself. Depending on the setup, you can even swap out the native database migration for other libraries within the language chosen. The popular web frameworks will naturally come bundled with the database migration features. If you use a popular language (Ruby, PHP, Python, etc.) or framework (Rails, Django, etc.), then there are well-documented libraries for data migration within the universe of the framework/language chosen. Option 1: Use a Framework/Language-Dependent Library In this section, I'll cover the two most common ways to perform a database migration. In other words, how you perform a database migration depends heavily on the specific tool you use for the task. Unfortunately, there are no standards at all for database migration files, which means we can't get into too much detail on how to create them.
![dbschema ways to write dbschema ways to write](https://dbschema.com/documentation/img/automation/code-samples-dialog.png)
You also need to know (at least conceptually) how to perform a database migration. Now you know what a database migration is. But why handwrite and accidentally introduce bugs when you can make use of tools to autogenerate the database migrations? How Do You Perform a Database Migration? Of course, you can write your own custom database migration scripts in the SQL files. So unless you want to handwrite your database migration in SQL format, there are no real standards across how the migration files are created. In actual fact, Liquibase can produce migration changes (or changesets, as they like to call them) in multiple formats such as XML and JSON. This is an example of a migration file in Rails. That way, your granular schema changes are reflected as code that can be captured with any version control software. These granular changes are typically reflected as separate scripted files. I mentioned how database migrations basically track granular changes to your database schema (and sometimes to your data as well). Granular Changes Are Generated as Individual Scripted Files Now that you know how database migrations came about, let me walk you through what they actually entail. This should give a beginner developer the tools to quickly learn the key ideas behind data migration and also learn potential pitfalls to avoid when using database migration as part of his or her development toolbox. I'll break this up into three sections, covering what happens during the migration process, the common tools used, and the pitfalls that can crop up during database migration. With that in mind, today I'll give you the big-picture view of what database migration involves and how to do it in an active development environment. Can you imagine being able to roll back granular changes to the schema as you write your code? Too often, I find that articles about database migration don't discuss what it means to actively do one, as a developer. There are even standalone database migration software libraries like Flyway and Liquibase. But database migration as a concept is not restricted to popular web frameworks. So popular frameworks like Rails and Django added ORM and database migration (also known as schema migration) as part of their offerings. The key idea was this: since developers can make changes in code that are easy to roll back using Git, why can't developers do the same thing when it comes to schema changes? After all, any reasonable new feature involves code and schema changes.
![dbschema ways to write dbschema ways to write](https://dbschema.com/documentation/img/interface/interface.png)
Around the same time Git got popular, the trend for writing web-based applications using object-relational mapping (ORM) libraries also became well known.