Installer: Running Your First Update

The main Liquibase command you will use is update, which applies any unrun changes in your changelog to your database.

Step One: Run Update

To run your first update:

1. Open a command-line or Terminal app.
2. Navigate to your ...examples/sql directory (or xml).
3. In your command prompt run liquibase update.

You should see a message saying Update has been successful.

Step Two: Check your Developer Console Page

Next, refresh your developer database console page.

You should now see the following tables added to the object view:

• COMPANY
• DATABASECHANGELOG
• DATABASECHANGELOGLOCK
• PERSON

By running liquibase update, your database now matches the desired database state as defined by the changelog script.

The DATABASECHANGELOG and DATABASECHANGELOGLOCK tables are Liquibase-metadata tables, the COMPANY and PERSON tables were created by the changelog.

Step Three: Open your changelog File

Now, open the com/example/sample.changelog.xml or com/example/sample.changelog.sql file in your favorite text editor.

In each file you can see how changes were defined as a series of changesets. Each changeset is uniquely identified by the id and author fields. Liquibase uses these fields to track what changes have been run and what has not.

When you ran the update command, Liquibase evaluated which changesets had not been run against your target database, then ran them.

Step Four: Add New changesets

Running the update command allowed your developer database to match the defined state. Now that they match, you can start adding additional changes you need.

If you have not run your first update, please follow the instructions in the previous sections before completing this section.

In this example, we will add a new changesets to create a works for column in the PERSONS table.

To add this changeset, open the sample changelog file in your existing editor, and one of the following to then END of the file:

XML changelog example code

<changeSet  id="3"  author="your.name">  
    <addColumn  tableName="person">  
        <column  name="worksfor_company_id"  type="int"/>  
    </addColumn>  
</changeSet>  

<changeSet  id="4"  author="your.name">  
    <addForeignKeyConstraint  constraintName="fk_person_worksfor"  
         baseTableName="person"  baseColumnNames="worksfor_company_id"  referencedTableName="company"  referencedColumnNames="id"/>  
</changeSet>

SQL changelog example code

--changeset your.name:4  
ALTER  TABLE  person  ADD  worksfor_company_id  INT;  

--changeset your.name:5  
ALTER  TABLE  person  ADD  CONSTRAINT  fk_person_worksfor  FOREIGN  KEY  (worksfor_company_id)  REFERENCES  company(id);

Note: It’s best practice to wrap every statement in its own changeset block.

Now, run liquibase update again & refresh your database console. You will see the new column on the PERSON table.

Step Five: Promoting Changes

Now that we added a new changeset and the database structure is what we want, we are ready to apply those changes to our integration database.

At this time in the workflow, you should commit your changelog to version control and/or build an artifact containing it, however, for this tutorial we will run it directly against our other database.

To apply the changes to the integration database run: liquibase --url=jdbc:h2:tcp://localhost:9090/mem:integration update

By passing along the --url parameter, you override the url value specified in the liquibase.properties file, but still use all the other parameters in the file.

After running update against the integration database, you should now see the COMPANY and PERSON tables in your integration web console.

Next Up: