EXPRESSION Field Type

Below are some examples of the EXPRESSION field type. 

Example 1:
Here is an example of an expression that calculates the volume of a pipe in gallons based on the pipes diameter in inches and length in feet.  This expression assumes you have fields in your layer called "Diameter" and "GIS Length".
   ([GIS Length]*(([Diameter]/2)*([Diameter]/2)*3.1416)/144)*7.48

Example 2:
Expressions can also be used to generate useful text values.  An expression like the one below could be used to generate a hyperlink to online SCADA information about your lift stations.  Note how it uses a "Name" field from the layer to create a deep link to that specific lift station's web page.
   "http://example.com/LiftStationData.asp?id=[Name]"