Oracle XSQL- P6 pot

bind-params=”string” Ordered list of XSQL parameter names that will bind to JDBC bind variables.. When this action is used, the XSQL page processor executes the PL/SQL block included in

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</EMPLOYEES_ROW>

</EMPLOYEES>

</ROW>

</ROWSET>

Oracle objects and collections also appear as nested structures in the canonical rep-resentation The following example shows a single row with an object and a collection:

<YOUR_OBJECT_COLUMN_NAME>

<ATTRIBUTE1>Value1</ATTRIBUTE1>

</YOUR_OBJECT_COLUMN_NAME>

<YOUR_COLLECTION_NAME>

<YOUR_COLLECTION_NAME_ITEM>

</YOUR_COLLECTION_NAME_ITEM>

<YOUR_COLLECTION_NAME_ITEM>

</YOUR_COLLECTION_NAME_ITEM>

</YOUR_COLLECTION_NAME>

</ROW>

</ROWSET>

Formatting Dates

Because most applications use dates at some point, it is very important to understand how XSQL works with dates XSQL uses date formats that act as masks A date format

is a combination of different symbols that represent different parts of the date-time stamp XSQL uses date formats both when retrieving information from the database and when putting information into it When retrieving information, XSQL writes the date to output in accordance with the date format When inputting information, it assumes that dates are in the format specified by the date format

The characters that represent different parts of the date format are listed in Table 5.5 Padding for variable-length data can be supplied by repeating the symbol For exam-ple, if you want 08 to represent 8 A.M., you put hh in the format string

Table 5.5 Date Format Symbols

MM Month in year as number 07

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Table 5.5 Date Format Symbols (Continued)

MMM Month in year as word July

h Hour in A.M./P.M (1-12) 12

H Hour in day (0-23) 0

s Second in minute 55

F Day of week in month 2 (2nd Wed in July)

a A.M./P.M marker PM

k Hour in day (1~24) 24

K Hour in A.M./P.M (0~11) 0

z Time zone Pacific Standard Time

‘ Escape for text

Table 5.6 shows a couple of examples of formatting dates

Table 5.6 Example Date Formats

“MM.dd.yyyy G ‘at’ hh:mm:ss z” 05/02/2002 AD at 15:08:56 PDT

“EEE, MMM d, ‘’yy” Sun, Apr 10, ‘02

“hh ‘o’’clock’ a, zzzz” 12 o’clock PM, Pacific Daylight Time

“yyyyy.MM.dd HH:mm” 2002.July.10 23:08

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Several of the XSQL built-in actions use date formats All of them use the same format.

Other Built-in Actions

This section exposes the details of the rest of the XSQL actions The next two chapters will look more deeply in to several of these actions as you learn about modifying the database and passing parameters All of these actions work in the same manner as the xsql:queryaction with which you are already familiar You specify attributes and a value for the action element

xsql:dml

DML stands for Data Manipulation Language It means that you are going to change something in the database The xsql:dml element is used for statements of change, including insertions, updates, deletions, and even creation and deletion of database objects Though you should heed the warning against actually deleting whole tables, the xsql:dml element is very useful for processing input to your database You can also use it to execute PL/SQL blocks

The following example uses a PL/SQL block to insert two records into the database and commit them As you will learn in Chapter 9, PL/SQL can be used to do a great variety of tasks You can call a wide variety of procedures, use conditional logic, and even process results The example here is very pedestrian, but you will see more com-plex examples in Chapter 9

<dml>

<xsql:dml>

begin insert into emp (empno, ename) values (8000,’Joe Schmoe’);

insert into emp (empno, ename) values (8001,’Billy Blue’);

commit;

end;

</xsql:dml>

</dml>

<query>

<xsql:query>

select * from emp

</xsql:query>

</query>

</page>

When you look at the results of the example, you will see that there is little result that comes back from the xsql:dml tag All that you can expect is either an error message if something goes wrong or an element that tells you the number of rows that are affected You will learn in Chapter 14 how best to return to the user the status of a DML request There are a couple of attributes that you can use to configure the behavior of the xsql:dmlelement They are described in Table 5.7

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Table 5.7 xsql:dml Attributes

ATTRIBUTE NAME DESCRIPTION

commit=”boolean” If yes, a commitment is issued on the

connection after a successful execution of the DML statement Default is no

bind-params=”string” Ordered list of XSQL parameter names that

will bind to JDBC bind variables More on this later in the chapter

error-statement=”boolean” If set to no, the SQL statement that

generated the error won’t be included in the output This keeps your users (and possibly hackers) from being able to reverse engineer your database schema Default is yes

xsql:ref-cursor-function

This action interacts with a PL/SQL function A PL/SQL function returns a value at the end of execution Some PL/SQL functions return cursors, acting essentially like a result set The difference is that the PL/SQL function can assemble the cursor by using condi-tional logic and several SQL statements across a variety of tables Only PL/SQL functions that return the type REF CURSOR can be called from a xsql:ref-cursor-function action

Assume that you have a function whose name is MyPackage.MyFunction and that it returns a REF CURSOR You would call it as follows:

<?xml version=”1.0”?>

<ref-cursor>

<xsql:ref-cursor-function>

MyPackage.MyFunction(1)

</xsql:ref-cursor-function>

</ref-cursor>

</page>

This action works very similarly to the xsql:query action, except that it calls a PL/SQL function instead of issuing SQL statements directly It is little surprise, then, that almost all of the attributes for xsql:query work for xsql:ref-cursor -function There is only one exception—the fetch-size attribute can’t be applied here You will learn more about using PL/SQL in Chapter 9

xsql:include-owa

It may be the case that you have stored procedures in the database that generate XML It’s quite reasonable that you might want to reuse that logic and have that XML included in your XSQL page This is the purpose of the xsql:include-owa action There are two standard Oracle Web Agent (OWA) packages (HTP and HTF) that will

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write to the server-side page buffer When this action is used, the XSQL page processor executes the PL/SQL block included in the action, assuming that the functions and pro-cedures of the HTP and HTF are being used to write XML to the server-side page buffer The XSQL page processor then grabs the output out of the page buffer and inserts it in

to the outgoing XSQL page It is the responsibility of the PL/SQL programmer to ensure that the XML is well formed Here is an example of how to use this action:

<xsql:include-owa>

PL/SQL Block using HTP and/or HTF packages to write to server-side page buffer

</xsql:include-owa>

There are a couple of attributes that can be used with the xsql:include-owa action They are described in Table 5.8

xsql:include-request-params

This action is a utility action designed to make it easier to write XSLT stylesheets It formats every parameter and its value to XML, including not only form- and URL-based parameters but also session parameters and cookies The usage is very simple, and there are no optional attributes Just put the following into your XSQL document:

<xsql:include-request-params/>

In its place you will get XML back in the following form If there are no session variables or cookies, those elements will not occur

<ParamName1>value1</ParamName1>

<ParamName2>value2</ParamName2>

</parameters>

<SessionVarName1>value1</SessionVarName1>

<SessionVarName2>value2</SessionVarName2>

</session>

<cookieName1>value1</cookieName1>

<cookieName2>value2</cookeName2>

</cookies>

</request>

When you look at XSLT in depth in Chapter 13, you will learn more about the use-fulness of this action

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Table 5.8 xsql:include-owa Attributes

bind-params=”string” Ordered list of XSQL parameter names that

will bind to JDBC bind variables More on this later in the chapter

error-statement=”boolean” If set to no, the SQL statement that generated

the error won’t be included in the output This keeps your users (and possibly hackers) from being able to reverse engineer your database schema Default is yes

xsql:include-param

This action allows you to include a single parameter in to your XML datagram It is essentially a scaled back, specific version of the xsql:include-request-params action It gives you an easy way to make your parameters and their values available to your XSLT stylesheets Here is the syntax:

<xsql:include-param name=”paramname”/>

The name attribute is required, and there are no optional attributes

xsql:include-xml

This action allows you to include XML in your datagram from any URL Relative URLs will point to files in your local Web space, whereas absolute URLs can grab the resource from anywhere on the Web The XML retrieved must be well formed Here is how you use it:

<xsql:include-xml href=”URL”/>

The href attribute is required, and there are no optional attributes

xsql:set-page-param

The xsql:set-page-param action allows you to set a page-private parameter for the XSQL page You can set the parameter either as text, as text and other parameter values, or as the result of a SQL statement There are two different syntaxes for this attribute The first syntax covers the first two cases:

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This will set paramname=value You may be wondering how you would use this syntax to assign the value of another parameter You will learn more about this later in the chapter, when you read about passing parameters For now, here is one example:

<xsql:set-page-param name=”new-param” value=”{@org-param}”/>

This will set the value of org-param as the value of new-param

The other syntax is quite a bit more interesting With it you can set parameters based

on SQL statements An example follows The value assigned is that of the first column

of the first row For clarity, it is best to structure your SQL statements so that only one row and one column will be returned

<xsql:set-page-param name=”sql-based-param”>

SQL statement

</xsql:set-page-param>

This action has a couple of attributes, detailed in Table 5.9 The name attribute is required

xsql:set-session-param

The xsql:set-session-param action allows you to set a parameter on the current browser user’s HTTP session This session is controlled by the Web server, but it gen-erally ends after a time out or when the browser is closed This action has an effect only when you are using XSQL in conjunction with Java servlets Nothing happens if the XSQL request object or XSQL command line encounters this action in a page that it is processing

The syntax behaves very much like the syntax for the xsql:set-page-param action You can set a parameter’s value in two ways You can set it directly, as follows:

<xsql:set-session-param name=”paramname” value=”value”/>

You can also set the parameter’s value by issuing a SQL statement The value assigned is that of the first column of the first row For clarity, it is best to structure your SQL statements so that only one row and one column will be returned

Table 5.9 xsql:set-page-param Attributes

name=”string” Name of the page-private parameter to set bind-params=”string” Ordered list of XSQL parameter names

that will bind to JDBC bind variables More on this later in the chapter

ignore-empty-value=”boolean” If yes, the parameter won’t be set if the

value that would be assigned is an empty string Default is no

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<xsql:set-session-param name=”sql-based-param”>

SQL statement

</xsql:set-session-param>

The xsql:set-session-param action has several attributes, listed in Table 5.10 The name attribute is required

xsql:set-cookie

This action sets an HTTP cookie to a specified value This action has an effect only when you are using XSQL in conjunction with Java servlets Nothing happens if the XSQL request object or XSQL command line encounters this action in a page that it is processing

The syntax behaves very much like the syntax for the xsql:set-page-param action You can set a parameter’s value in two ways You can set it directly, as follows:

<xsql:set-cookie name=”paramname” value=”value”/>

<xsql:set-cookie name=”sql-based-param”>

SQL statement

</xsql:set-cookie>

The xsql:set-cookie action has several attributes, listed in Table 5.11 The name attribute is required

Table 5.10 xsql:set-session-param Attributes

name=”string” Name of the session parameter to set

bind-params=”string” Ordered list of XSQL parameter names

that will bind to JDBC bind variables

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