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 merge your data in one column, follow these steps:

Step 1: Add the mergeColumns Change Type to your changeset with the needed attributes as it is shown in the examples.

Step 2: 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 The name of the catalog all
column1Name The name of the column containing the first half of the data all all
column2Name The name of the column containing the second half of the data all all
finalColumnName The name of the column to create all all
finalColumnType The data type of the column to create all all
joinString The string to place between the values from column1 and column2 (may be empty) all
schemaName The name of the schema all
tableName The name of the table containing the columns to join all all 
<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>
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
{
   "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"
             }
           }
         ]
       }
     }
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;

Database support

Database Notes Auto rollback
DB2/LUW Supported No
DB2/z Not Supported No
Derby Not Supported No
Firebird Supported No
H2 Supported No
HyperSQL Supported No
INGRES Supported No
Informix Supported No
MariaDB Supported No
MySQL Supported No
Oracle Supported No
PostgreSQL Supported No
SQL Server Supported No
SQLite Supported No
Sybase Supported No
Sybase Anywhere Supported No