Attributes in ArcGIS

ArcGIS Attributes typically have two default fields:

• FID - ESRI's internal identifier, and
• Shape - Actual spatial data.

Adding Fields

You'll need to add new fields to attribute tables in ArcGIS. To add a new field:

1. Select "Add Field" from the Options Menu.
2. Name the Field.
3. Select the type of data.
4. Be careful with "Precision." (I never change it)

 

When adding a new field into a Shapefile, you must make sure that the Shapefile is not marked as Read-only and that you are not presently in an Edit Session.

Checking the Shapefile

1. Use "File Explorer" or "My Computer."
2. Select all the files for the Shapefile by:
   1. Shift-clicking each file, or
   2. Drag the cursor over all of them.
3. Right-click on one of the selected files.
4. If "Read-Only" is checked:
   1. Uncheck it, and
   2. Click "OK."

Checking the Edit Session

1. Right-Click on the menu bar.
2. Select "Editor"
3. If "Start Editing" is grayed out:
   1. Select "Stop Editing."

Naming Fields

Arc only allows 10 characters when naming fields. Remember, you will be using the Name in calculations and queries!

Select the Field Properties

Select the "Type" of attribute carefully. I recommend only using "Long Integer" for integer values and "Double" for floating point values.

Short Integer	16-bit Integer (5 digits)
Long Integer	32-bit Integer (9 digits)
Float	32-bit Floating Point
Double	64-bit Floating Point
Text	Up to 254 Characters
Date	MM/DD/YYYY Format

Precision Can Change "Type"

Note that in ArcGIS, if you change the "Precision" of an attribute, ArcGIS may change the "Type" without telling you.

Delete a Field

You must be outside of an edit session to delete fields within the attribute table.

Select by Attributes

Select by attributes is a powerful and commonly used tool in ArcGIS. This tool allows you to create simple or complex SQL queries to select features in layers.

"Select by Attributes" is available in the "Attribute Table" by clicking on the icon in the upper left.

 

You'll want to select the column or field, and an operator, and then a value. You can use "Get Unique Values" to view the available values in the column.

More Select by Attributes

Below are a series of videos for you to learn the full capabilities of the "Select by Attributes" tool. Watch the first video and then practice using Select by Attribute in ArcGIS and then move on to the next video.

Select by attributes with numbers:

Select by attributes with strings:

Select by attributes with dates:

Test Your Knowledge

 

Additional Resources

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