Liquibase Change Types mergeColumns

Some columns in tables store the merged value of multiple-column data. Liquibase provides mergeColumns Change Type that joins values of two columns and stores in a new column.

mergeColumns Change Type will delete both columns and create a new joined column.

<?xml version="1.1" encoding="UTF-8" standalone="no"?>
<databaseChangeLog xmlns="http://www.liquibase.org/xml/ns/dbchangelog" xmlns:ext="http://www.liquibase.org/xml/ns/dbchangelog-ext" xmlns:pro="http://www.liquibase.org/xml/ns/pro" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog-ext http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-ext.xsd http://www.liquibase.org/xml/ns/pro http://www.liquibase.org/xml/ns/pro/liquibase-pro-latest.xsd http://www.liquibase.org/xml/ns/dbchangelog http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-latest.xsd">
	<changeSet author="wesome" id="1695467351190-1">
		<createTable catalogName="appledb" tableName="apple">
			<column autoIncrement="true" name="apple_id" type="BIGINT">
				<constraints nullable="false" primaryKey="true" />
			</column>
			<column name="apple_name" type="VARCHAR(255)" />
			<column name="apple_taste" type="VARCHAR(255)" />
			<column defaultValueComputed="CURRENT_TIMESTAMP" name="current_date_time" type="datetime" />
		</createTable>
	</changeSet>
	<changeSet author="wesome" id="1695467351190-2">
		<insert catalogName="appledb" tableName="apple">
			<column name="apple_name" value="Macintosh" />
			<column name="apple_taste" value="Sweet" />
			<column name="current_date_time" valueDate="now()" />
		</insert>
		<insert catalogName="appledb" tableName="apple">
			<column name="apple_name" value="Fuji" />
			<column name="apple_taste" value="Salty" />
			<column name="current_date_time" valueDate="now()" />
		</insert>
		<insert catalogName="appledb" tableName="apple">
			<column name="apple_name" value="Gala" />
			<column name="apple_taste" value="Sour" />
			<column name="current_date_time" valueDate="now()" />
		</insert>
	</changeSet>
	<changeSet author="wesome" id="1692701200879-4">
		<mergeColumns catalogName="appleDb" column1Name="apple_name" column2Name="apple_taste" finalColumnName="apple_name-apple_taste" finalColumnType="varchar(255)" joinString="-" schemaName="appleDb" tableName="apple" />
	</changeSet>
</databaseChangeLog>

liquibase.properties (update changeLog File file format with SQL, XML, YAML, JSON as per changelog.mysql.)

changeLogFile=changelog.mysql.xml
liquibase.command.url:jdbc:mysql://localhost:3306/appleDb?createDatabaseIfNotExist=true&autoReconnect=true&useSSL=false&allowPublicKeyRetrieval=true
liquibase.command.username : root
liquibase.command.password : rootroot

Run command liquibase update

The result can verified by running the query

SELECT * FROM appleDb.apple;