LiquiBase Quick-Start

The database changelog file is where all database changes are listed. It is XML based, so start with an empty XML file:

<?xml version="1.0" encoding="UTF-8"?>
 
<databaseChangeLog
  xmlns="http://www.liquibase.org/xml/ns/dbchangelog/1.6"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog/1.6
         http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-1.6.xsd">
 
</databaseChangeLog>

Each change set is uniquely identified by an “id” attribute and an “author” attribute. These two tags, along with the name and package of the changelog file uniquely identify the change. If only an “id” needed to be specified, it would be too easy to accidentally duplicate them, especially when dealing with multiple developers and code branches. Including an “author” attribute minimizes the chances of duplications.

Think of each change set as an atomic change that you want to apply to your database. It's usually best to include just one change in your change set, but more are allowed and can make sense if you are insert multiple rows that should be added as a single transaction. LiquiBase will attempt to run each change set as a single transaction, but many databases will silently commit and resume transactions for certain commands (create table, drop table, etc.)

<?xml version="1.0" encoding="UTF-8"?>
 
<databaseChangeLog
  xmlns="http://www.liquibase.org/xml/ns/dbchangelog/1.6"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog/1.6
         http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-1.6.xsd">
 
    <changeSet id="1" author="bob">
        <createTable tableName="department">
            <column name="id" type="int">
                <constraints primaryKey="true" nullable="false"/>
            </column>
            <column name="name" type="varchar(50)">
                <constraints nullable="false"/>
            </column>
            <column name="active" type="boolean" defaultValue="1"/>
        </createTable>
    </changeSet>
 
</databaseChangeLog>

There are many ways to execute your change log including via command line, Ant, Maven, Grails, and a servlet listener.

liquibase --driver=com.mysql.jdbc.Driver \
     --classpath=/path/to/classes \
     --changeLogFile=com/example/db.changelog.xml \
     --url="jdbc:mysql://localhost/example" \
     --username=user \
     --password=asdf \
     migrate

You will see that your database now contains a table called “department”. Two other tables are created as well: “databasechangelog” and “databasechangeloglock”. The databasechangelog table contains a list of all the statements that have been run against the database. The databasechangeloglock table is used to make sure two machines don't attempt to modify the database at the same time.

This quick-start guide is designed to get you started with LiquiBase. For a full description of all its capabilities, see the LiquiBase Manual. You can also view recorded sessions on LiquiBase or visit the mailing list.