What are the different formats supported by Liquibase for writing changelogs?

Liquibase supports four main formats for writing changelogs:

1. XML - The original and most feature-complete format
2. YAML - Human-readable alternative to XML
3. JSON - Useful for programmatic generation
4. SQL - Direct SQL statements with Liquibase formatting comments

Example of the same changeset in different formats:

XML:

<changeSet id="1" author="developer">
    <createTable tableName="products">
        <column name="id" type="int" autoIncrement="true">
            <constraints primaryKey="true"/>
        </column>
    </createTable>
</changeSet>

YAML:

changeSet:
  id: 1
  author: developer
  changes:
    - createTable:
        tableName: products
        columns:
          - column:
              name: id
              type: int
              autoIncrement: true
              constraints:
                primaryKey: true

SQL:

--liquibase formatted sql
--changeset developer:1
CREATE TABLE products (
    id INT AUTO_INCREMENT PRIMARY KEY
);