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</div><hr /><div id="sdodasrel.examples.one-table" class="section">
<h2 class="title">One-table examples</h2>
<p class="para">
The following set of examples all use the Relational DAS to work with
a data graph containing just one application data object, a single
company and the data just to be found the company table. These examples
do not exercise the power of SDO or the Relational DAS and of course
the same result could be achieved more economically with direct SQL
statements but they are intended to illustrate how to work with the
Relational DAS.
</p>
<p class="para">
For this very simple scenario it would be possible to simplify the
database metadata to include just the company table - if that were done
the second and third arguments to the constructor and the column
specifier used in the query example would become optional.
</p>
<p class="para">
<div class="example" id="example-5467">
<p><strong>Example #1 Creating a data object</strong></p>
<div class="example-contents"><p>
The simplest example is that of creating a single data object and
writing it to the database. In this example a single company object
is created, its name is set to 'Acme', and the Relational DAS is
called to write the changes to the database. The company name is
set here using the property name method. See the
<a href="sdo.examples.html" class="link">Examples</a>
section on the SDO extension for other ways of accessing the
properties of an object.
</p></div>
<div class="example-contents"><p>
Data objects can only be created when you have a data object to
start with, however. It is for that reason that the first call
to the Relational DAS here is to obtain a root object. This is
in effect how to ask for an empty data graph - the special root
object is the true root of the tree. The company data object is
then created with a call to
<span class="function"><strong>createDataObject()</strong></span>
on the root object. This creates the company data object and inserts
it in the graph by inserting into a multi-valued containment property
on the root object called 'company'.
</p></div>
<div class="example-contents"><p>
When the Relational DAS is called to apply the changes a simple
insert statement 'INSERT INTO company (name) VALUES ("Acme");'
will be constructed and executed. The auto-generated primary key
will be set into the data object and the change summary will be reset,
so that it would be possible to continue working with the same data
object, modify it, and apply the newer changes a second time.
</p></div>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">require_once </span><span style="color: #DD0000">'SDO/DAS/Relational.php'</span><span style="color: #007700">;<br />require_once </span><span style="color: #DD0000">'company_metadata.inc.php'</span><span style="color: #007700">;<br /><br /></span><span style="color: #FF8000">/**************************************************************<br />* Construct the DAS with the metadata<br />***************************************************************/<br /></span><span style="color: #0000BB">$das </span><span style="color: #007700">= new </span><span style="color: #0000BB">SDO_DAS_Relational </span><span style="color: #007700">(</span><span style="color: #0000BB">$database_metadata</span><span style="color: #007700">,</span><span style="color: #DD0000">'company'</span><span style="color: #007700">,</span><span style="color: #0000BB">$SDO_containment_metadata</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">/**************************************************************<br />* Obtain a root object and create a company object underneath.<br />* Make a simple change to the data object. <br />***************************************************************/<br /></span><span style="color: #0000BB">$root </span><span style="color: #007700">= </span><span style="color: #0000BB">$das </span><span style="color: #007700">-> </span><span style="color: #0000BB">createRootDataObject</span><span style="color: #007700">();<br /></span><span style="color: #0000BB">$acme </span><span style="color: #007700">= </span><span style="color: #0000BB">$root </span><span style="color: #007700">-> </span><span style="color: #0000BB">createDataObject</span><span style="color: #007700">(</span><span style="color: #DD0000">'company'</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">$acme</span><span style="color: #007700">-></span><span style="color: #0000BB">name </span><span style="color: #007700">= </span><span style="color: #DD0000">"Acme"</span><span style="color: #007700">;<br /><br /></span><span style="color: #FF8000">/**************************************************************<br />* Get a database connection and write the object to the database<br />***************************************************************/<br /></span><span style="color: #0000BB">$dbh </span><span style="color: #007700">= new </span><span style="color: #0000BB">PDO</span><span style="color: #007700">(</span><span style="color: #0000BB">PDO_DSN</span><span style="color: #007700">,</span><span style="color: #0000BB">DATABASE_USER</span><span style="color: #007700">,</span><span style="color: #0000BB">DATABASE_PASSWORD</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$das </span><span style="color: #007700">-> </span><span style="color: #0000BB">applyChanges</span><span style="color: #007700">(</span><span style="color: #0000BB">$dbh</span><span style="color: #007700">, </span><span style="color: #0000BB">$root</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
<p class="para">
<div class="example" id="example-5468">
<p><strong>Example #2 Retrieving a data object</strong></p>
<div class="example-contents"><p>
In this example a single data object is retrieved from the database
- or possibly more than one if there is more than one company
called 'Acme'. For each company returned, the
<var class="varname"><var class="varname">name</var></var>
and
<var class="varname"><var class="varname">id</var></var>
properties are echoed.
</p></div>
<div class="example-contents"><p>
In this example the third argument to
<span class="function"><strong>executeQuery()</strong></span>,
the column specifier is needed as there are other tables in the
metadata with column names of
<var class="varname"><var class="varname">name</var></var>
and
<var class="varname"><var class="varname">id</var></var>.
If there were no possible ambiguity it could be omitted.
</p></div>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">require_once </span><span style="color: #DD0000">'SDO/DAS/Relational.php'</span><span style="color: #007700">;<br />require_once </span><span style="color: #DD0000">'company_metadata.inc.php'</span><span style="color: #007700">;<br /><br /></span><span style="color: #FF8000">/**************************************************************<br />* Construct the DAS with the metadata<br />***************************************************************/<br /></span><span style="color: #0000BB">$das </span><span style="color: #007700">= new </span><span style="color: #0000BB">SDO_DAS_Relational </span><span style="color: #007700">(</span><span style="color: #0000BB">$database_metadata</span><span style="color: #007700">,</span><span style="color: #DD0000">'company'</span><span style="color: #007700">,</span><span style="color: #0000BB">$SDO_containment_metadata</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">/**************************************************************<br />* Get a database connection<br />***************************************************************/<br /></span><span style="color: #0000BB">$dbh </span><span style="color: #007700">= new </span><span style="color: #0000BB">PDO</span><span style="color: #007700">(</span><span style="color: #0000BB">PDO_DSN</span><span style="color: #007700">,</span><span style="color: #0000BB">DATABASE_USER</span><span style="color: #007700">,</span><span style="color: #0000BB">DATABASE_PASSWORD</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">/**************************************************************<br />* Issue a query to obtain a company object - possibly more if they exist<br />***************************************************************/<br /></span><span style="color: #0000BB">$root </span><span style="color: #007700">= </span><span style="color: #0000BB">$das</span><span style="color: #007700">-></span><span style="color: #0000BB">executeQuery</span><span style="color: #007700">(</span><span style="color: #0000BB">$dbh</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">'select name, id from company where name="Acme"'</span><span style="color: #007700">,<br /> array(</span><span style="color: #DD0000">'company.name'</span><span style="color: #007700">, </span><span style="color: #DD0000">'company.id'</span><span style="color: #007700">) );<br /><br /></span><span style="color: #FF8000">/**************************************************************<br />* Echo name and id <br />***************************************************************/<br /></span><span style="color: #007700">foreach (</span><span style="color: #0000BB">$root</span><span style="color: #007700">[</span><span style="color: #DD0000">'company'</span><span style="color: #007700">] as </span><span style="color: #0000BB">$company</span><span style="color: #007700">) {<br /> echo </span><span style="color: #DD0000">"Company obtained from the database has name = " </span><span style="color: #007700">. <br /> </span><span style="color: #0000BB">$company</span><span style="color: #007700">[</span><span style="color: #DD0000">'name'</span><span style="color: #007700">] . </span><span style="color: #DD0000">" and id " </span><span style="color: #007700">. </span><span style="color: #0000BB">$company</span><span style="color: #007700">[</span><span style="color: #DD0000">'id'</span><span style="color: #007700">] . </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
<p class="para">
<div class="example" id="example-5469">
<p><strong>Example #3 Updating a data object</strong></p>
<div class="example-contents"><p>
This example combines the previous two, in the sense that in order
to be updated the object must first be retrieved. The application
code reverses the company name (so 'Acme' becomes 'emcA') and then the
changes are written back to the database in the same way that they
were when the object was created. Because the query searches for
the name both ways round the program can be run repeatedly to find
the company and reverse its name each time.
</p></div>
<div class="example-contents"><p>
In this example the same instance of the Relational DAS is reused
for the
<span class="function"><strong>applyChanges()</strong></span>,
as is the PDO database handle. This is quite alright; it also
alright to allow the previous instances to be garbage collected
and to obtain new instances. No state data regarding the graph
is held the Relational DAS once it has returned a data graph to
the application. All necessary data is either within the graph itself,
or can be reconstructed from the metadata.
</p></div>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">require_once </span><span style="color: #DD0000">'SDO/DAS/Relational.php'</span><span style="color: #007700">;<br />require_once </span><span style="color: #DD0000">'company_metadata.inc.php'</span><span style="color: #007700">;<br /><br /></span><span style="color: #FF8000">/**************************************************************<br />* Construct the DAS with the metadata<br />***************************************************************/<br /></span><span style="color: #0000BB">$das </span><span style="color: #007700">= new </span><span style="color: #0000BB">SDO_DAS_Relational </span><span style="color: #007700">(</span><span style="color: #0000BB">$database_metadata</span><span style="color: #007700">,</span><span style="color: #DD0000">'company'</span><span style="color: #007700">,</span><span style="color: #0000BB">$SDO_containment_metadata</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">/**************************************************************<br />* Get a database connection<br />***************************************************************/<br /></span><span style="color: #0000BB">$dbh </span><span style="color: #007700">= new </span><span style="color: #0000BB">PDO</span><span style="color: #007700">(</span><span style="color: #0000BB">PDO_DSN</span><span style="color: #007700">,</span><span style="color: #0000BB">DATABASE_USER</span><span style="color: #007700">,</span><span style="color: #0000BB">DATABASE_PASSWORD</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">/**************************************************************<br />* Issue a query to obtain a company object - possibly more if they exist<br />***************************************************************/<br /></span><span style="color: #0000BB">$root </span><span style="color: #007700">= </span><span style="color: #0000BB">$das</span><span style="color: #007700">-></span><span style="color: #0000BB">executeQuery</span><span style="color: #007700">(</span><span style="color: #0000BB">$dbh</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">'select name, id from company where name="Acme" or name="emcA"'</span><span style="color: #007700">,<br /> array(</span><span style="color: #DD0000">'company.name'</span><span style="color: #007700">, </span><span style="color: #DD0000">'company.id'</span><span style="color: #007700">) );<br /><br /></span><span style="color: #FF8000">/**************************************************************<br />* Alter the name of just the first company<br />***************************************************************/<br /></span><span style="color: #0000BB">$company </span><span style="color: #007700">= </span><span style="color: #0000BB">$root</span><span style="color: #007700">[</span><span style="color: #DD0000">'company'</span><span style="color: #007700">][</span><span style="color: #0000BB">0</span><span style="color: #007700">];<br />echo </span><span style="color: #DD0000">"obtained a company with name of " </span><span style="color: #007700">. </span><span style="color: #0000BB">$company</span><span style="color: #007700">-></span><span style="color: #0000BB">name </span><span style="color: #007700">. </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$company</span><span style="color: #007700">-></span><span style="color: #0000BB">name </span><span style="color: #007700">= </span><span style="color: #0000BB">strrev</span><span style="color: #007700">(</span><span style="color: #0000BB">$company</span><span style="color: #007700">-></span><span style="color: #0000BB">name</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">/**************************************************************<br />* Write the change back<br />***************************************************************/<br /></span><span style="color: #0000BB">$das</span><span style="color: #007700">-></span><span style="color: #0000BB">applyChanges</span><span style="color: #007700">(</span><span style="color: #0000BB">$dbh</span><span style="color: #007700">,</span><span style="color: #0000BB">$root</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
<p class="para">
<div class="example" id="example-5470">
<p><strong>Example #4 Deleting a data object</strong></p>
<div class="example-contents"><p>
Any companies called 'Acme' or its reverse 'emcA' are retrieved.
They are then all deleted from the graph with unset.
</p></div>
<div class="example-contents"><p>
In this example they are all deleted in one go by unsetting the
containing property (the property defining the containment
relationship). It is also possible to delete them individually.
</p></div>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">require_once </span><span style="color: #DD0000">'SDO/DAS/Relational.php'</span><span style="color: #007700">;<br />require_once </span><span style="color: #DD0000">'company_metadata.inc.php'</span><span style="color: #007700">;<br /><br /></span><span style="color: #FF8000">/**************************************************************<br />* Construct the DAS with the metadata<br />***************************************************************/<br /></span><span style="color: #0000BB">$das </span><span style="color: #007700">= new </span><span style="color: #0000BB">SDO_DAS_Relational </span><span style="color: #007700">(</span><span style="color: #0000BB">$database_metadata</span><span style="color: #007700">,</span><span style="color: #DD0000">'company'</span><span style="color: #007700">,</span><span style="color: #0000BB">$SDO_containment_metadata</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">/**************************************************************<br />* Get a database connection<br />***************************************************************/<br /></span><span style="color: #0000BB">$dbh </span><span style="color: #007700">= new </span><span style="color: #0000BB">PDO</span><span style="color: #007700">(</span><span style="color: #0000BB">PDO_DSN</span><span style="color: #007700">,</span><span style="color: #0000BB">DATABASE_USER</span><span style="color: #007700">,</span><span style="color: #0000BB">DATABASE_PASSWORD</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">/**************************************************************<br />* Issue a query to obtain a company object - possibly more if they exist<br />***************************************************************/<br /></span><span style="color: #0000BB">$root </span><span style="color: #007700">= </span><span style="color: #0000BB">$das</span><span style="color: #007700">-></span><span style="color: #0000BB">executeQuery</span><span style="color: #007700">(</span><span style="color: #0000BB">$dbh</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">'select name, id from company where name="Acme" or name="emcA"'</span><span style="color: #007700">,<br /> array(</span><span style="color: #DD0000">'company.name'</span><span style="color: #007700">, </span><span style="color: #DD0000">'company.id'</span><span style="color: #007700">) );<br /><br /></span><span style="color: #FF8000">/**************************************************************<br />* Delete any companies found from the data graph<br />***************************************************************/<br /></span><span style="color: #007700">unset(</span><span style="color: #0000BB">$root</span><span style="color: #007700">[</span><span style="color: #DD0000">'company'</span><span style="color: #007700">]);<br /><br /></span><span style="color: #FF8000">/**************************************************************<br />* Write the change(s) back<br />***************************************************************/<br /></span><span style="color: #0000BB">$das</span><span style="color: #007700">-></span><span style="color: #0000BB">applyChanges</span><span style="color: #007700">(</span><span style="color: #0000BB">$dbh</span><span style="color: #007700">,</span><span style="color: #0000BB">$root</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
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