Some Concepts That Underpin GIS - Introducing Geographic Information Systems with ArcGIS - page 81

7. Sewers should now be displayed by itself. Open the attribute table for Sewers by right-clicking
Sewers and, from the menu that appears, selecting Open Attribute Table. (Is the procedure to
open an attribute table in your Fast Facts File? If you didn't remember how to open an attribute
table, it should be.) Reduce the dimensions of the attribute table and position it so that you
can see it and the graphic image of the Sewers as well. On the Tools toolbar (which resembles
the Tools toolbar in ArcCatalog—zoom, pan, etc.), find the Full Extent Icon and click it to be sure
you are seeing the entire Sewers map. Then, press the Select Features icon (not the Select
Elements icon, which is also on the Tools toolbar). Now, click the northernmost sewer line. It
should turn cyan and the relevant row of the attribute table should be highlighted . Pick another
line and observe. Sort the records, in ascending order, according to Shape_Length. Click the
shortest arc you can find on the map and verify its length in the table.
8. In the table, click in the small box to the far left of the last record. The selected record
becomes highlighted and so will the equivalent line .
I went through the last few steps to reinforce the point (that maybe you now understand so well you
don't want to hear it anymore): A GIS is a special case of an information system whose database is the
marriage of a (geo)graphic database and an attribute database.
Next, you look very briefly at the capacity of ArcGIS to let you add a completely separate database table
to the Table of Contents, view such a table, and then join it together with a feature class attribute table so
that the information in the separate table becomes part of the attribute table.
9. Click the New Map File icon on the Standard toolbar. You want to open a blank map. Don't save
changes. Add the Landcover feature class from
___IGIS-Arc_ YourInitials \Wildcat_Boat_Data
\Wildcat_Boat.mdb\Area_Features.
10. Open the Landcover attribute table. Notice that the table contains the column LC_CODE but no
indication of what the codes mean. Undock the table if it is docked, and then close the table.
11. Click the List By Source button at the top of the Layers window. Add, using the ArcCatalog tree
(in the side pane), the database table
___IGIS-Arc_ YourInitials \Other_Data\LC_Code&Type.dbf.
Right-click LC_Code&Type and Open the table. What are the columns of the LC_Code&Type
Table?
________, _______________________, ____________________.
Dismiss the table window.
12. Right-click Landcover in the Table Of Contents. Choose Joins and Relates > Join to bring up
a Join Data window. You want to join attributes from a table. In box number one—the field in
the layer Landcover that the join will be based on—select LC_Code from the dropdown menu.
Such a field is called a key field . In box number two, the table you want to join to the layer is,
of course, LC_Code&Type. In box number three, which may have been automatically filled in for