Programming instructions

Enhancing the Trip Maintenance application 125

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</cfif>

The first two buttons are the easiest to handle because they do not require building any

new pages. Therefore, you will implement the functionality for the

Search and Delete

buttons first.

Linking the Trip Detail page to the Trip Search page

The ColdFusion cflocation tag navigates from the current page to a target HTML or

CFML page. The URL attribute contains the name of the target page and any

arguments. The code to navigate to the search page (tripsearch.cfm) follows:

Deleting the current trip record shown on the Trip Detail page

Before you can write the code to delete a trip, you must understand the underlying SQL

statement to delete rows from the trips table.

SQL DELETE Statement

The SQL DELETE statement removes existing rows in a relational table. The format of

the DELETE statement is as follows:

DELETE FROM table_name WHERE column_name = some_value

Consider a database table named Clients that holds information about people with the

following rows:

To delete everyone from New York from the table, use the following statement:

DELETE FROM Clients WHERE City = 'New York'

After the database management system processed the preceding statement, the table

would contain the following row only:

To ensure that the Trip Maintenance application deletes only the proper trip, you must

use the unique tripID key when issuing the SQL DELETE. The RecordID field holds

the tripID. Therefore, using the hidden

RecordID input tag from the Trip Detail page,

the following SQL statement deletes a row from the Trips table reads:

LastName FirstName Address City

Jones Tom 50 Main St New York

Adamson Anita 521 Beacon St Boston

Green Peter 1 Broadway New York

LastName FirstName Address City

Adamson Anita 521 Beacon St Boston