MACROMEDIA COLDFUSION 4.5-CFML LANGUAGE Manuale Utente Scaricare il pdf (Pagina 6)

6 CHAPTER 30 Extending ColdFusion with CFX

Table 30.7 C++ Methods for Working with Queries

METHOD DESCRIPTION

pRequest->AddQuery(name, columns) Creates a new query. Specify the name of the query

as a

LPCSTR, and columns as a CCFXStringSet

(similar to an array of strings).

pQuery->AddRow() Adds a row to the query.

pQuery->SetData(row, col, value) Places the value (which must be a LPCSTR) into the

query at the row and column position you specify.

pRequest->GetQuery() Retrieves the query (if any) that was passed to the

CFX tag. Returns a

CCFXQuery object, or null if no

QUERY attribute was provided to the tag.

pQuery->GetColumns() Returns the names of the query’s columns, as a

CFXStringSet, which is similar conceptually to an

array of strings. You can use any of the methods

listed in Table 30.8 on the returned

CFXStringSet.

For instance, you can use

GetIndexForString() to

ﬁnd the index position of a column by name; that

index position could then be used in the

GetData()

or SetData() functions.

pQuery->GetData(row, col) Returns the value in the query at the given row and

column position. The value is always returned as a

LPCSTR.

pQuery->GetName() Returns the name of the query (as a LPCSTR), as it is

known in the calling ColdFusion page.

pQuery->GetRowCount() Returns the number of rows in the query, as an int.

To pass a query to a CFX tag, the name of the query must be speciﬁed as an attribute named QUERY

(you don’t get to determine the name of the attribute). So, if a query=”FilmsQuery” attribute is sup-

plied when the tag is called, then the

getQuery() method will grab the query for use inside of the

CFX tag. You can then use

getRecordCount(), getColumns(), and getData() to refer to the data in

the query.

Because standard C++ doesn’t have a built-in notion of an ordered set of strings, the CFX API

includes an additional class type called

CFXStringSet, which is similar conceptually to an array of

strings in Java. An object of this type is returned if you call the

GetAttributes() method listed in

Table 30.3 or the

GetColumns() method from Table 30.7. Similarly, to create a new query object,

you ﬁrst create a new

CFXStringSet, add column names to the string set using AddString(), then

pass the string set to the

AddQuery() method (also listed in Table 30.7). The methods supported by

this class are listed in Table 30.8.

NOTE

This part of the CFX API is only included in the C++ version. There is no need for it in Java, which already includes the notion of a

string set (the

String[] type).

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