MACROMEDIA COLDFUSION MX 61-DEVELOPING COLDFUSION MX, Руководство по разработке, Страница: 62 / 860

62 Chapter 3: Using ColdFusion Variables
You can use either of the following methods to reference elements stored in a structure:
•
StructureName.KeyName
•
StructureName["KeyName"]
The following examples show these methods:
depts.John="Sales"
depts["John"]="Sales"
When you assign an existing structure to a new variable, ColdFusion does
not
create a new
structure. Instead, the new variable accesses the same data (location) in memory as the original
structure variable. In other words, both variables are references to the same object.
For example, the following line creates a new variable, myStructure2, that is a reference to the
same structure as the myStructure variable:
<cfset myStructure2=myStructure>
When you change the contents of myStructure2, you also change the contents of myStructure. To
copy the contents of a structure, use the ColdFusion
Duplicate
function, which copies the
contents of structures and other complex data types.
Structure key names can be the names of complex data objects, including structures or arrays.
This lets you create arbitrarily complex structures.
For more information on using structures, see Chapter 5, “Using Arrays and Structures,”
on page 103 .
Queries
A query object , sometimes referred to as a query, query result, or record set, is a complex
ColdFusion data type that represents data in a set of named columns, similar to the columns of a
database table. The following ColdFusion tags can create query objects:
•
cfquery
•
cfdirectory
•
cfhttp
•
cfldap
•
cfpop
•
cfprocresult
In these tags, the
name
attribute specifies the query object’s variable name. The
QueryNew
function also creates query objects.
When you assign a query to a new variable, ColdFusion does not copy the query object. Instead,
both names point to the same record set data. For example, the following line creates a new
variable, myQuery2, that references the same record set as the myQuery variable:
<cfset myQuery2 = myQuery>
If you make changes to data in myQuery, myQuery2 also shows those changes.
You reference query columns by specifying the query name, a period, and the column name; for
example:
myQuery.Dept_ID