Basic GIS Tools - Attribute Tables

Concepts:
   attributes
   attribute table
   selecting records

Attribute table
If you recall back to the section on features and attributes, every feature (a thing's location) has one or more attributes (what we know about a thing).  This is a fundamental concept of GIS.  These attributes have to be stored somewhere, and in GIS they are put in a database table, which we refer to as the attribute table.  Each GIS layer has its own attribute table where the attributes for the features in that layer are stored.  Each feature has one record (row) in the attribute table, so the number of records in a layer's attribute table is always equal to the number of features.  The different attributes we store for each feature are called attribute fields.

To see a layer's attribute table, right-click the layer name to bring up its context menu, and choose 'Open Attribute Table'.  Here is an example:


When the attribute table opens, it will show the fields and records for that particular layer.  Here is an example:


Just like previously when you selected features, you can also select records in a table.  There are two ways to do this - interactive selecting and select by attributes.

With interactive selecting, you just click on the grey 'button' to the left of the record.  Hold down CTRL to select multiple records.  The record will be highlighted as it is selected.  Here is an example:

The 'Select by Attributes' tool is exactly the same as the one for selecting features, and is found on the 'Options' menu.  You can also choose to only display selected records in an attribute table - this is useful when you have selected 20 out of 80,000 records and don't want to scroll through the whole table looking for them.

Every attribute table record is dynamically linked to its feature, so if you select a record, the feature will automatically be selected (and vice-versa).

Finally, some buttons and tools exist to help you browse an attribute table, these are in the field context menu.  Right-click a field name to see this.  Here is an example: