Add Field (Data Management)

Adds a field to the table of a feature class, feature layer and/or raster catalog.

Learn more about how Add Field works

Usage tips

See ArcGIS data types for a detailed explanation of field types.

A field of type raster allows you to have a raster image as an attribute. It is stored within or alongside the geodatabase. This is helpful when a picture is the best way to describe a feature. Precision, scale and length can not be set for fields of type raster.

Coverages, standalone tables, feature classes from ArcSDE and personal or file geodatabases, layer files, raster catalogs, and shapefiles will work as valid input for this command. VPF and CAD feature data overlays will not work, since they are read-only formats that are not native to ArcGIS.

The added field will always be displayed at the end of the table.

The Field Length parameter is only applicable on fields of type text or blob.

For coverages, shapefiles and dBase tables, if field type defines a character, blanks are inserted for each record. If field type defines a numeric item, zeros are inserted for each record.

For geodatabases, if field type defines a character or number <null> is inserted into each record if the FieldIsNullible parameter default is accepted.

A shapefile does not support alias for fields, so you cannot add a field alias to a shapefile.

It is only possible to add a field that is not nullable to an empty geodatabase feature class or table. Add Field cannot add a field that is not nullable when the rows already exist.

The Field Domain parameter can call an existing domain from a feature class in a personal, file or SDE geodatabase.

The precision and scale of a field describe the maximum size and precision of data that can be stored in the field. The precision describes the number of digits that can be stored in the field and the scale describes the number of decimal places for float and double fields. For example, if the field value is 54.234 then scale = 3 and precision = 5.Use the following guidelines for choosing the correct field type for a given precision and scale:
- When you create a float, double, or integer field and specify 0 for precision and scale, the tool will attempt to create a binary type field if the underlying database supports it. Personal and file geodatabases support only binary type fields, and precision and scale are ignored.
- When you create float and double fields and specify a precision and scale, if your precision is greater than 6, use a double; otherwise, use a float. If you create a double field and specify a precision of 6 or less, a float field is created. If you create a float field and specify a precision greater than 6, a double field is created.
- If you specify a scale of 0 and a precision of 10 or less, you should be creating integer fields. When creating integer fields, your precision should be 10 or less, or your field may be created as double.

When creating a new field in a geodatabase feature class or table, you can specify the field's type, but not it's precision, and scale. Even if the dialog allows you to add a value for precision or scale it will be ignored during execution.

The name of an existing domain must be specified for the Field Domain parameter. Enter invalid domain names or values will not cause the tool to fail but it will be ignored and no domain will be set for the field.

Fields set as REQUIRED are permanent and you will not be able to delete them with future processing. To allow for deletion at a later time set the field to NON_REQUIRED (the default).

For more information about adding fields see, Adding and deleting fields or About tabular data sources

For more information about the RASTER type option see, Raster datasets as attributes

The following environment affects this tool: workspace.

Syntax

AddField_management (in_table, field_name, field_type, field_precision, field_scale, field_length, field_alias, field_is_nullable, field_is_required, field_domain)

Parameter	Explanation	Datatype
Input Table (Required)	The input table to which the specified field will be added. The field will be added to the existing input table and will not create a new output table. Fields can be added to feature classes of ArcSDE, file or personal geodatabases, coverages, shapefiles, raster catalogs, standalone tables, and/or layers.	Table View \| Raster Layer
Field Name (Required)	The name of the field that will be added to the Input Table.	String
Field Type (Required)	The field type used in the creation of the new field. TEXT—Names or other textual qualities. FLOAT—Numeric values with fractional values within a specific range. DOUBLE—Numeric values with fractional values within a specific range. SHORT—Numeric values without fractional values within a specific range; coded values. LONG—Numeric values without fractional values within a specific range. DATE—Date and/or Time. BLOB—Images or other multimedia. RASTER—Raster images.	String
Field Precision (Optional)	Describes the number of digits that can be stored in the field. All digits are counted no matter what side of the decimal they are on. If the input table is a personal or file geodatabase the field precision value will be ignored.	Long
Field Scale (Optional)	Sets the number of decimal places stored in a field. This parameter is only used in Float and Double data field types. If the input table is a personal or file geodatabase the field scale value will be ignored.	Long
Field Length (Optional)	The length of the field being added. This sets the maximum number of allowable characters for each record of the field. This option is only applicable on fields of type text or blob.	Long
Field Alias (Optional)	The alternate name given to the field name. This name is used to give more descriptive names to cryptic field names. The field alias parameter only applies to geodatabases and coverages.	String
Field Is Nullable (Optional)	A geographic feature where there is no associated attribute information. These are different from zero or empty fields and are only supported for fields in a geodatabase. NON_NULLABLE—The field will not allow null values. NULLABLE—The field will allow null values. This is the default.	Boolean
Field Is Required (Optional)	Specifies whether the field being created is a required field for the table; Only supported for fields in a geodatabase. NON_REQUIRED—The field is not a required field. This is the default. REQUIRED—The field is a required field. This means new records must contain a value for the field. Required fields are permanent and can not be deleted.	Boolean
Field Domain (Optional)	Used to constrain the values allowed in any particular attribute for a table, feature class, or subtype in a geodatabase. You must specify the name of an existing domain for it to be applied to the field.	String

Data types for geoprocessing tool parameters

Script Example

import arcgisscripting
gp = arcgisscripting.create()

# Set a default workspace
gp.workspace = "c:\\test_data"

# Set a toolbox
gp.toolbox = "management"

try:
    # Add a field to this shapefile, of type LONG
    gp.addfield ("harvestable.shp", "year", "long", "9")

    # Adds a geodatabase stand-alone feature class of type LONG
    gp.addfield ("redlands.mdb\streets", "ref_ID", "long", "9", "#", "#", "refcode", "NULLABLE", "REQUIRED", "#")

except:
    # If an error occurs when running Addfield, print out the error message.
    print gp.GetMessages(2)

Add Field (Data Management)

Usage tips

Syntax

See Also