`column`

The column tag specifies information about columns you create or modify with Change Types like createTable, createIndex, addColumn, dropColumn, insert, and others. You can specify one or multiple columns in a single changeset.

Uses

Use the column tag to define the behavior of your table columns in different ways. For example, setting the defaultValue attribute on a column specifies its default value. Setting the value attribute sets all rows existing to the specified value without modifying the column default.

Some Change Type that interact with table columns, like addPrimaryKey, do not use the <column> tag. Instead, they use their own attributes like columnNames to refer to existing columns specified with the <column> tag.

Available attributes

Note: Because the <column> tag has multiple uses, not every attributes is valid in each context it is used in.

Attribute	Description
`name`	The name of the column.
`type`	The column data type.
`value`	Sets all fields in the column to the specified value. The value will be surrounded by quote marks. Nested quote marks will be escaped.
`afterColumn`	Controls the placement of a new column added with the `addColumn` Change Type. Note: Only one of `beforeColumn`, `afterColumn`, or `position` is allowed.
`autoIncrement`	The auto-increment column. Ignored on databases that do not support auto-increment or identity functionality.
`beforeColumn`	Controls the placement of a new column added with the `addColumn` Change Type. Note: Only one of `beforeColumn`, `afterColumn`, or `position` is allowed.
`computed`	Used if the value in `name` is a function rather than a column name.
`defaultValue`	The default value for fields in the column. Note: If you don't set the first value, the `defaultValueXXX` is used in the order it appears.
`defaultValueBoolean`	The default boolean value for fields in the column.
`defaultValueComputed`	The default value that is returned from a function or procedure call. Contains the function to call.
`defaultValueDate`	The default date and time value for column. The value is specified in one of the following forms: `YYYY-MM-DD`, `hh:mm:ss`, or `YYYY-MM-DDThh:mm:ss`.
`defaultValueNumeric`	The default numeric value for fields in the column.
`descending`	Defines whether a column is in descending order in the index if it is used in a `createIndex` command. Default value is `false` (ascending).
`encoding`	The name of the encoding (specified in java.nio.Charset javadoc, e.g. `"UTF-8"`) of the CLOB file (specified in `valueClobFile`) contents. Note: This attribute is used only when `valueClobFile`attribute is specified. Otherwise, it is ignored.
`incrementBy`	The value of each step by auto-increment. Ignored on databases that do not support auto-increment or identity functionality.
`position`	Controls the placement of a new column added with the `addColumn` Change Type. Note: Only one of `beforeColumn`, `afterColumn`, or `position` is allowed.
`remarks`	A short description of the column (column comment).
`startWith`	The value auto-increment starts at. Ignored on databases that do not support auto-increment or identity functionality.
`valueBlobFile`	The path to a file whose contents will be written as a BLOB (binary large object). The path to the changelog file location must be either absolute or relative. An example of an absolute path is: `/usr/local/somefile.dat` on Unix or `c:\Directory\somefile.dat` on Windows. Note: Refer to java.io.File javadoc for the details of what to consider relative or absolute path.
`valueBoolean`	The boolean value to set fields in the column to. The actual value string inserted depends on the database implementation.
`valueClobFile`	The path to a file whose contents will be written as a CLOB (character large object). The path to the changelog file location must be either absolute or relative. An example of an absolute path is: `/usr/local/somefile.dat` on Unix or `c:\Directory\somefile.dat` on Windows. Note: Refer to java.io.File javadoc for the details of what to consider relative or absolute path.
`valueComputed`	The value that is returned from a function or procedure call. Contains the function to call.
`valueDate`	The date and time value to set the column to. Accepts the following formats: `YYYY-MM-DD`, `hh:mm:ss`, or `YYYY-MM-DDThh:mm:ss`.
`valueNumeric`	The numeric value to set fields in the column to. The value will not be escaped and will not be nested in quote marks.

To help make scripts database-independent, the following generic data types are automatically converted to the correct database implementation:

BIGINT
BLOB
BOOLEAN
CLOB
CURRENCY
DATE
DATETIME
TIME
UUID

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)

Available sub-tags

Tag	Description
`constraints`	Constraint definitions

Constraints sub-tag

The <constraints> tag contains information about constraints on the column.

Available attributes

Attribute	Description
`checkConstraint`	Defines whether to validate the defined check constraint. Default: database-dependent
`deleteCascade`	Sets `DELETE CASCADE`.
`deferrable`	Defines whether constraints are deferrable. Default: database-dependent
`foreignKeyName`	The foreign key name.
`initiallyDeferred`	Defines whether constraints are initially deferred. Default: database-dependent
`notNullConstraintName`	The `NOT NULL CONSTRAINT` name.
`nullable`	Defines whether the column is nullable. Default: database-dependent
`primaryKey`	Defines whether the column is a primary key. Default: database-dependent
`primaryKeyName`	The name of the primary key.
`primaryKeyTablespace`	The tablespace to use for the defined primary key.
`unique`	Defines whether a unique clause should be applied. Default: database-dependent
`uniqueConstraintName`	The unique constraint name.
`references`	The foreign key definition.
`referencedColumnNames`	The name of the column.
`referencedTableCatalogName`	The name of the catalog.
`referencedTableName`	The name of the table.
`referencedTableSchemaName`	The name of the schema.
`validateForeignKey`	Defines whether to validate the defined foreign key constraint. Default: database-dependent
`validateNullable`	Defines whether to validate the defined not null constraint. Default: database-dependent
`validatePrimaryKey`	Defines whether to validate the defined primary key constraint. Default: database-dependent
`validateUnique`	Defines whether to validate the defined unique constraint. Default: database-dependent

Note: YAML and JSON changelogs using the column tag must nest it within a columns tag.

XML example

<changeSet author="liquibase-docs" id="addColumn-example"> 
	<addColumn catalogName="cat"  
			schemaName= "public"
			tableName="person" >
		<column name="address" 
			position="2"  
			type="varchar(255)"/>  
		<column afterColumn="id" 
			name="name"  
			type="varchar(50)" >  
			<constraints nullable="false" />  
		</column>  
	</addColumn>  
</changeSet>

YAML example

databaseChangeLog:
  - changeSet:
      id: addColumn-example
      author: liquibase-docs
      changes:
        - addColumn:
            tableName: person
            columns:
            - column:
                name: middlename
                type: varchar(50)

JSON example

{
  "changeSet":{
  "id":"addColumn-example",
  "author":"liquibase-docs",
  "changes":[
     {
       "addColumn":{
         "catalogName":"cat",
         "columns":[
            {
              "column":{
                 "name":"address",
                 "position":2,
                 "type":"varchar(255)"
        	   } 
            },
            {
              "column":{
                 "afterColumn":"id",
                 "constraints":{
                    "nullable":false
        		 },
                 "name":"name",
                 "type":"varchar(50)"
               }
             }
           ],
           "schemaName":"public",
           "tableName":"person"
          }
        }
      ]
    }
  }

SQL example

ALTER TABLE cat.person ADD address VARCHAR(255) NULL,  
ADD name VARCHAR(50) NOT NULL AFTER `id`;

column

Uses

Available attributes

Available sub-tags

Constraints sub-tag

Available attributes

Related links

`column`