Programming instructions

Enhancing the Trip Maintenance application 123
<cfelseif IsDefined("Form.btnLast.X")>
ORDER BY tripID DESC
</cfif>
</cfquery>
<cfif TripQuery.RecordCount is 1>
<cflocation url="tripdetail.cfm?ID=#TripQuery.tripID#">
<cfelese>
<cflocation url="tripdetail.cfm?ID=#Form.RecordID#">
</cfif>
Reviewing the code
The following table describes the code used to process the navigation button requests:
Code Explanation
<cfquery
name="TripQuery"
dataSource="compasstravel"
maxRows=1>
The cfquery tag identifies that a query
named "TripQuery" will be executed
against the "CompassTravel" data
source. The number of rows returned
cannot exceed 1 (maxRows=1).
SELECT tripID FROM trips
The SQL SELECT statement will always
start with "SELECT tripID FROM trips".
<cfif IsDefined("Form.btnPrev.X")>
WHERE tripID < #Form.RecordID#
ORDER BY tripID DESC
<cfelseif IsDefined("Form.btnNext.X")>
WHERE tripID > #Form.RecordID#
ORDER BY tripID
<cfelseif IsDefined("Form.btnFirst.X")>
ORDER BY tripID
<cfelseif IsDefined("Form.btnLast.X")>
WHERE tripID > #Form.RecordID#
ORDER BY tripID DESC
</cfif>
</cfquery>
The cfif tag checks if the user pressed
a navigation button on the browse page.
The X property is checked since the
buttons on the detail page use image
type HTML input tags. The X property is
a mouse offset that gets sent when you
click a graphic button.
The WHERE and ORDER BY clauses
will vary depending on the navigation
button clicked by the user.
<cfif TripQuery.RecordCount is 1>
<cflocation
url="tripdetail.cfm?RecordID=#TripQuery.tripID#">
<cfelse>
<cflocation
url="tripdetail.cfm?RecordID=#Form.RecordID#">
</cfif>
The cfif tag checks if the query
returned a row to display. If it did, use that
tripID to form a URL to navigate to
using the cflocation tag. If the query
returned no rows, navigate back to the
detail page with current record id passed
in the hidden form variable RecordID.