Summary
Adds a new field to a table or the table of a feature class or feature layer, as well as to rasters with attribute tables.
Usage
For 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.
The Field Length parameter is only applicable to fields of type text. If a length is not specified, the length will default to 255.
For geodatabases, if field type defines a character or number, <null> is inserted into each record if the Field Is Nullable parameter is checked (field_is_nullable="NULLABLE" in Python).
A nonnullable field cannot be added to a nonempty geodatabase feature class or table.
A shapefile does not support aliases for fields, so you cannot add a field alias to a shapefile.
The Field Domain parameter can use an existing domain from a feature class in a geodatabase. The name of an existing domain must be provided. Providing an invalid domain name or value will not cause the tool to fail, but the invalid name or value will be ignored and no domain will be set for the field.
The precision and scale of a field describe the maximum precision and size 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, 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. 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 the 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 will be created. If you create a float field and specify a precision greater than 6, a double field will be created.
- If you specify a scale of 0 and a precision of 10 or less, create an integer field. When creating an integer field, specify a precision of 10 or less, or your field may be created as a double.
When creating a new field in a geodatabase feature class or table, you can specify the field's type but not its precision and scale. Even if the dialog box allows you to add a value for precision or scale, the value will be ignored during execution.
Required fields are permanent and cannot be deleted. To allow for deletion at a later time, set the field to nonrequired (the default).
A field of type raster allows you to include a raster image as an attribute. It is stored in or alongside the geodatabase. This is helpful when an image is the best way to describe a feature. Precision, scale, and length cannot be set for fields of type raster.
Syntax
arcpy.management.AddField(in_table, field_name, field_type, {field_precision}, {field_scale}, {field_length}, {field_alias}, {field_is_nullable}, {field_is_required}, {field_domain})| Parameter | Explanation | Data Type |
in_table | 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 in geodatabases, shapefiles, coverages, stand-alone tables, raster catalogs, rasters with attribute tables, and layers. | Mosaic Layer; Raster Layer; Table View |
field_name | The name of the field that will be added to the input table. | String |
field_type | Specifies the field type of the new field.
| String |
field_precision (Optional) | The number of digits that can be stored in the field. All digits are counted regardless of which side of the decimal they are on. If the input table is a file geodatabase, the field precision value will be ignored. | Long |
field_scale (Optional) | 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 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 parameter is only applicable to fields of type text. | Long |
field_alias (Optional) | The alternate name given to the field name. This name is used to describe cryptic field names. This parameter only applies to geodatabases. | String |
field_is_nullable (Optional) | Specifies whether the field can contain null values. Null values are different from zero or empty fields and are only supported for fields in a geodatabase.
| Boolean |
field_is_required (Optional) | Specifies whether the field being created is a required field for the table. Required fields are only supported in a geodatabase.
| Boolean |
field_domain (Optional) | Constrains 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 |
Derived Output
| Name | Explanation | Data Type |
| out_table | The updated input table. | Table |
Code sample
The following Python window script demonstrates how to use the AddField function in immediate mode.
import arcpy
arcpy.env.workspace = "C:/data/airport.gdb"
arcpy.AddField_management("schools", "ref_ID", "LONG", 9, "", "", "refcode",
"NULLABLE", "REQUIRED")The following stand-alone script demonstrates how to use the AddField function.
# Name: AddField_Example2.py
# Description: Add a pair of new fields to a table
# Import system modules
import arcpy
# Set environment settings
arcpy.env.workspace = "C:/data/airport.gdb"
# Set local variables
inFeatures = "schools"
fieldName1 = "ref_ID"
fieldPrecision = 9
fieldAlias = "refcode"
fieldName2 = "status"
fieldLength = 10
# Execute AddField twice for two new fields
arcpy.AddField_management(inFeatures, fieldName1, "LONG", fieldPrecision,
field_alias=fieldAlias, field_is_nullable="NULLABLE")
arcpy.AddField_management(inFeatures, fieldName2, "TEXT",
field_length=fieldLength)Environments
Licensing information
- Basic: Yes
- Standard: Yes
- Advanced: Yes