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How Add Field (Data Management) works |
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Release 9.2
Last modified November 29, 2010 |
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This tool adds a field to the feature layer, shapefile, or raster catalog.
Coverage and INFO table items are mapped based on a combination of their type and width. For example, an item of type I can map to a short integer, long integer, or double, depending on its width. For detailed information on item to field type mapping between coverages and the geodatabase, see the table below.
| Item Name | Item Width | Geodatabase Field Type |
| B | 4 | Long Integer |
| C | 1 - 320 | Text |
| D | 8 | Date |
| F | 4 | Float |
| F | 8 | Double |
| I | 1-4 | Short Integer |
| I | 5-9 | Long Integer |
| I | 10-16 | Double |
| N | 1-9 | Float |
| N | 10-16 | Double |
Each different shapefile and dBASE field type maps to a single geodatabase type independent of field size. The exception is the Number type field, which will map to a long integer if its number of decimals is zero and to a double if its number of decimals is greater than zero. For detailed information on dBASE field type to geodatabase field type mapping, see the table below.
| Field Type | Field Width | Geodatabase Field Type |
| Date | - | Date |
| Text | 1 - 255 | Text |
| Boolean | - | Text |
| Number | 1 - 16 (decimals = 0) | Long Integer |
| Number | 1 - 16 (decimals > 0) | Double |
All occurrences of "#" and "-" in INFO item names will be replaced with an underscore character. This includes COVER# and COVER-ID. Due to this substitution, item names "COVER_" and "COVER_ID" are reserved and should not exist in the input coverage's attribute tables. Coverage to Shapefile checks to see if the substitution will result in duplicate item names.
If an INFO item name is longer than 10 characters, a message will be displayed telling you the new field name that has been truncated to meet the dBASE limit. The Define mapping option will be automatically selected when this message is displayed.
The maximum record length for a dBASE data file is 4,000 bytes. The maximum for an INFO data file is 4,096 bytes. Coverage to Shapefile will issue a warning message if the dBASE limit is exceeded but will continue. The record length is the number of bytes required to define all the items or fields in a table.
The maximum number of fields for a dBASE data file is 255. Coverage to Shapefile will convert the first 255 items if this dBASE limit is exceeded.
For detailed information on item to field type mapping between coverages and shapefiles, see the table below.
| ArcInfo Data Types | dBASE Data Types |
| Type | Width | Output | Decimal | ################## |
| C | n | - | - | Character <expC>(n) |
| D | - | - | - | Date <expD> |
| B | 2 | - | - | Numeric <expN>(6,0) |
| B | 4 | - | - | Numeric <expN>(11,0) |
| I | n | - | - | Numeric <expN>(n,0) |
| N | n | - | m | Numeric <expN>(n,m) |
| F | - | n | m | Numeric <expN>(n,m) |
For detailed information on item to field type mapping between geodatabases and shapefiles, see the table below.
| Geodatabase Data Type | dBASE Item Type | dBASE Item Width |
| Object ID | N | 9 |
| Short Integer | N | 4 |
| Long Integer | N | 9 |
| Float | F | 13 |
| Double | F | 19 |
| Text | C | 255 |
| Date | D | 8 |
| Blob | N/A | N/A |
The maximum record length for an INFO table is 4,096 bytes. When the limit is exceeded, the table is converted, but the tool issues a warning message after the conversion that the table may be unusable.
INFO table item names are limited to 16 characters in length. Item names longer than the stated limits will be truncated at those limits.
If an item name is used more than once in the Output table, possibly due to truncation of item names exceeding the limit, the last two characters in the item name will be replaced by an underscore "_" and a number. The number will start with one and increase sequentially making each redundant item name unique.
BLOBs are not supported in INFO. Fields defined as BLOB data type will not be converted.
For detailed information on item to field type mapping between geodatabases and coverages, see the table below.
| Geodatabase Data Type | INFO Item Width | INFO Item Type | INFO output Width | INFO no. Decimals |
| Object ID | B | 4 | 9 | - |
| Short Integer | B |
|
5 | - |
| Long Integer | B | 4 | 9 | - |
| Float | F | 4 | 12 | 3 |
| Double | F | 8 | 18 | 5 |
| Text | C | 255 | 255 | - |
| Date | D | 8 | 10 | 0 |
| Blob | N/A | N/A | N/A | N/A |