mergeColumns

The mergeColumns Change Type concatenates the values in two columns and joins them with a string. The Change Type stores the resulting value in a new column.

Uses

You can typically use the mergeColumns Change Type when you want to combine the values from two columns into one.

Running the `mergeColumns` Change Type

To run this Change Type, follow these steps:

Add the Change Type to your changeset, as shown in the examples on this page.
Specify any required attributes. Use the table on this page to see which ones your database requires.
Deploy your changeset by running the update command:

liquibase update

Now, you should see a new merged column.

Available attributes

Name	Description	Required for	Supports
`catalogName`	Name of the catalog		all
`column1Name`	Name of the column containing the first half of the data	all	all
`column2Name`	Name of the column containing the second half of the data	all	all
`finalColumnName`	Name of the column to create	all	all
`finalColumnType`	Data type of the column. To help make scripts database-independent, Liquibase automatically converts the following generic data types to the correct database implementation: `BIGINT`, `BLOB`, `BOOLEAN`, `CHAR`, `CLOB`, `CURRENCY`, `DATE`, `DATETIME`, `DECIMAL`, `DOUBLE`, `FLOAT`, `INT`, `MEDIUMINT`, `NCHAR`, `NUMBER`, `NVARCHAR`, `SMALLINT`, `TIME`, `TIMESTAMP`, `TINYINT`, `UUID`, `VARCHAR`, `XML`. Also, specifying a `java.sql.Types.*` type is converted to the correct type as well. For example: `java.sql.Types.TIMESTAMP` `java.sql.Types.VARCHAR(255)`	all	all
`joinString`	The string to place between the values from `column1` and `column2` (may be empty)		all
`schemaName`	Name of the schema		all
`tableName`	Name of the table containing the columns to join	all	all

Examples

--liquibase formatted sql

--changeset liquibase-docs:mergeColumns-example
ALTER  TABLE  public.person  ADD  full_name  VARCHAR(255)  NULL;
UPDATE  cat.person  SET  full_name  =  CONCAT_WS('A String', 
first_name,last_name);
ALTER  TABLE  public.person  DROP  COLUMN  first_name;
ALTER  TABLE  public.person  DROP  COLUMN  last_name;

databaseChangeLog:
-  changeSet:
    id:  mergeColumns-example
    author:  liquibase-docs
    changes:
    -  mergeColumns:
        catalogName:  cat
        column1Name:  first_name
        column2Name:  last_name
        finalColumnName:  full_name
        finalColumnType:  varchar(255)
        joinString:  A String
        schemaName:  public
        tableName:  person

{
    "databaseChangeLog": [
        {
            "changeSet": {
                "id": "mergeColumns-example",
                "author": "liquibase-docs",
                "changes": [
                    {
                        "mergeColumns": {
                            "catalogName": "cat",
                            "column1Name": "first_name",
                            "column2Name": "last_name",
                            "finalColumnName": "full_name",
                            "finalColumnType": "varchar(255)",
                            "joinString": "A String",
                            "schemaName": "public",
                            "tableName": "person"
                        }
                    }
                ]
            }
        }
    ]
}

<databaseChangeLog
    xmlns="http://www.liquibase.org/xml/ns/dbchangelog"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:ext="http://www.liquibase.org/xml/ns/dbchangelog-ext"
    xmlns:pro="http://www.liquibase.org/xml/ns/pro"
    xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog
        http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-latest.xsd
        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">

    <changeSet  author="liquibase-docs"  id="mergeColumns-example">
        <mergeColumns  catalogName="cat"
            column1Name="first_name"
            column2Name="last_name"
            finalColumnName="full_name"
            finalColumnType="varchar(255)"
            joinString="A String"
            schemaName="public"
            tableName="person"/>
    </changeSet>

</databaseChangeLog>

Database support