Book VII 5 in Java

Drawer Code 39 Extended in Java Book VII 5

Consider the query that we use in the variable example in the Creating variables with <CFSET> section, earlier in the chapter: <CFQUERY datasource= cfcodeexplorer name= GetArtists > SELECT * FROM artists WHERE ARTISTID=#ArtistNumber# </CFQUERY>< This query returns information from all the columns in the artists table, namely ADDRESS CITY FAX LASTNAME POSTALCODE THEPASSWORD Each of these columns becomes a variable that can be output to the screen using a <CFOUTPUT> tag To use them, surround the column name with pound signs (#) So, for example, to output FIRSTNAME, you would use #FIRSTNAME# ARTISTID EMAIL FIRSTNAME PHONE STATE

ColdFusion generates a variety of variables that you can use in your applications These variables work just like variables that you create, and they re called in a similar fashion For example, if you want to show the operating system of the server that ColdFusion is running on, you can use the following resident variable (meaning it s active in ColdFusion at all times): <CFOUTPUT>#ServerOSName#</CFOUTPUT> For a complete listing of these resident variables that ColdFusion generates, check out the CFML reference guide in the Using ColdFusion Help files, accessible by pressing Ctrl+F1 within Dreamweaver

Hundreds of different functions are available to ColdFusion developers, and they do everything from creating a date to generating random numbers Although there are numerous ColdFusion functions, nearly all of them do one of the following four things:

Create new data and data structures Evaluate some type of data to determine its existence or format Evaluate some type of data to produce some new type of data Change the composition of some type of data

To give you some idea of the breadth of functions that are available, Macromedia puts them into 17 different categories (plus an Other category), with many functions being represented in more than one category We list all these categories in Table 5-1 and provide a brief description of the kinds of functions found in each group

Table 5-1

Creating, evaluating, and manipulating arrays Converting array, list, XML, and URL information into other formats Creating and formatting dates and times Checking whether various objects are defined or meet various criteria Formatting different kinds of data, such as currency, decimal formats, and number formats Evaluating different kinds of dynamic data, such as Boolean searches or string expressions Extending the functionality of ColdFusion to other data types, such as XML Performing searches in conjunction with ColdFusion s built-in searching tools Setting, converting, and evaluating currency, time, and location for other countries Testing length, sorting, converting to arrays, and appending lists Performing advanced calculations on data Other functions that don t fall into any of these categories Manipulating and evaluating ColdFusion queries Authenticating users and encrypting content Containing or manipulating string data Creating, manipulating, and evaluating ColdFusion structures Interacting with or getting information from the server Reading and transformation of XML documents

Display and formatting functions Dynamic evaluation functions Extensibility functions Full-text search functions International functions List functions Mathematical functions Other functions Query functions Security Functions String functions Structure functions System functions XML functions

Functions can be called in a few different ways: As part of a CFML tag: An example of this kind of function is IsDefined, which checks to see if a variable is defined The IsDefined function looks like this: <CFIF IsDefined( SomeVariable )> As part of defining a variable: An example of this kind of function is arrayNew(n), which creates an array (a collection of data) in n dimensions The arrayNew function is called from within a <CFSET> tag, as follows: <CFSET MyArray = arrayNew(1)> When outputting a variable: An example of this kind of function is DateFormat, which enables you to change the way the date looks DateFormat can be called as follows, where date is a variable that represents a date: #DateFormat(date, mm-dd-yyyy )# From within another function: It s not uncommon that functions support calling other functions to provide some value Take the following example: <CFSET discountprice = DollarFormat(Evaluate(price (price * discount))) > In this case, we are setting a variable discountprice using the DollarFormat function, and within that function using the Evaluate function to perform some basic arithmetic functions Going through each of the ColdFusion functions is beyond the scope of this book, but the following sections show you how to get started with the five most useful ColdFusion functions for beginners