Skip to main content
summaryrefslogblamecommitdiffstats
blob: 9a48136628eb575d0a65447aac9aa334cd26819e (plain) (tree)
1
2
3
4
5



                                                                   
                                        

























                                                                                               
                                                                                                                                                                                                                                                                                                                        












                                                                                                                                                                                                                                                                               


                                                               



                              


                                                                                               



                                                                                                                                  

                                                                                                                                                                       








                
                                                       





                                        
                                                                                                                                                                                       



                                                                                                                                                                                                                                                                                                             


                                                               



                              

                                                                                                                                                                                                                                                      

                                                                                                     
                                                                                                           







































                                                                                                                                                                                                
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<!-- Run date = May 9, 2007 10:03:43 -->
<meta name="OAC_IGNORE_SKIP_NAV" content="true" />
<title>Many-to-one mapping</title>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii" />
<meta http-equiv="Content-Style-Type" content="text/css" />
<meta http-equiv="Content-Script-Type" content="text/javascript" />
<meta name="generator" content="Oracle DARB XHTML Converter - Version 4.5.3 Build 02" />
<meta name="date" content="2005-07-10T12:57:20+08:00" />
<meta name="robots" content="all" scheme="http://www.robotstxt.org/" />
<meta name="doctitle" content="Many-to-one mapping" />
<meta name="relnum" content="Release 1.0.0" />
<meta name="partnum" content="" />
<link rel="copyright" href="dcommon/html/cpyr.htm" title="Copyright" type="text/html" />
<link rel="stylesheet" href="dcommon/css/blafdoc.css" title="Oracle BLAFDoc" type="text/css" />
<link rel="start" href="../../index.htm" title="Home" type="text/html" />
<link rel="contents" href="toc.htm" title="Contents" type="text/html" />
</head>
<body>
<p><a id="BABHFAFJ" name="BABHFAFJ"></a></p>
<div class="sect2"><!-- infolevel="all" infotype="General" -->
<table class="simple oac_no_warn" summary="" cellspacing="0" cellpadding="0" width="100%">
<tr valign="bottom">
<td align="left" width="86%">
<h1>Many-to-one mapping</h1>
</td>
</tr>
</table>
<p><a id="sthref133" name="sthref133"></a><a id="sthref134" name="sthref134"></a><a id="sthref135" name="sthref135"></a><a id="sthref136" name="sthref136"></a>Use a <span class="bold">Many-to-One</span> mapping to defines a single-valued association to another entity class that has many-to-one multiplicity.</p>
<ol type="1" start="1">
<li>
<p>In the <a href="ref_persistence_outline.htm#BABEGGFE">JPA Structure view</a>, select the field to map. The <a href="ref_persistence_map_view.htm#BABIFBAF">JPA Details view (for attributes)</a> displays the properties for the selected.</p>
</li>
<li>
<p>In the <span class="gui-object-title">Map As</span> field, select <span class="gui-object-action">Many-to-One</span>.</p>
</li>
<li>
<p>Use this table to complete the <a href="ref_mapping_general.htm#CACBHFIJ">General information</a> fields JPA Details view.</p>
<div class="inftblruleinformal">
<table class="RuleInformal" title="This table lists the fields ion the General tab for this mapping." summary="This table lists the fields ion the General tab for this mapping." dir="ltr" border="1" width="100%" frame="border" rules="all" cellpadding="3" cellspacing="0">
<thead>
<tr align="left" valign="top">
<th align="left" valign="bottom" id="r1c1-t11">Property</th>
<th align="left" valign="bottom" id="r1c2-t11">Description</th>
<th align="left" valign="bottom" id="r1c3-t11">Default</th>
</tr>
</thead>
<tbody>
<tr align="left" valign="top">
<td align="left" id="r2c1-t11" headers="r1c1-t11">Target Entity</td>
<td align="left" headers="r2c1-t11 r1c2-t11">The entity to which this attribute is mapped.</td>
<td align="left" headers="r2c1-t11 r1c3-t11">null
<p>You do not need to explicitly specify the target entity, since it can be inferred from the type of object being referenced.</p>
</td>
</tr>
<tr align="left" valign="top">
<td align="left" id="r3c1-t11" headers="r1c1-t11">Fetch Type</td>
<td align="left" headers="r3c1-t11 r1c2-t11">Defines how data is loaded from the database. See <a href="ref_mapping_general.htm#CACGGGHB">"Fetch Type"</a> for details.
<ul>
<li type="disc">
<p>Eager</p>
</li>
<li type="disc">
<p>Lazy</p>
</li>
</ul>
</td>
<td align="left" headers="r3c1-t11 r1c3-t11">Eager</td>
</tr>
</tbody>
</table>
<br /></div>
<!-- class="inftblruleinformal" --></li>
<li>
<p>Use this table to complete the fields on the <a href="reference007.htm#CACFCEJC">Join Columns Information</a> tab in the <span class="gui-object-title">JPA Details</span> view.</p>
<div class="inftblruleinformal">
<table class="RuleInformal" title="This table lists the fields in the Persistence Properties view for this mapping." summary="This table lists the fields in the Persistence Properties view for this mapping." dir="ltr" border="1" width="100%" frame="border" rules="all" cellpadding="3" cellspacing="0">
<thead>
<tr align="left" valign="top">
<th align="left" valign="bottom" id="r1c1-t12">Property</th>
<th align="left" valign="bottom" id="r1c2-t12">Description</th>
<th align="left" valign="bottom" id="r1c3-t12">Default</th>
</tr>
</thead>
<tbody>
<tr align="left" valign="top">
<td align="left" id="r2c1-t12" headers="r1c1-t12">Join Column</td>
<td align="left" headers="r2c1-t12 r1c2-t12"><a id="sthref137" name="sthref137"></a><a id="sthref138" name="sthref138"></a>Specify a mapped column for joining an entity association. This field corresponds to the <code>@JoinColum</code> attribute.
<p>Select <span class="bold">Override Default</span>, then Add, Edit, or Remove the join columns.</p>
</td>
<td align="left" headers="r2c1-t12 r1c3-t12">By default, the mapping is assumed to have a single join.</td>
</tr>
</tbody>
</table>
<br /></div>
<!-- class="inftblruleinformal" --></li>
</ol>
<p>Eclipse adds the following annotations to the field:</p>
<pre xml:space="preserve" class="oac_no_warn">
@JoinTable(joinColumns=@JoinColumn(name="<span class="italic">&lt;JOIN_COLUMN&gt;</span>"), 
    name = "<span class="italic">&lt;JOIN_TABLE_NAME&gt;</span>")
@ManyToOne(targetEntity=<span class="italic">&lt;TARGET_ENTITY&gt;</span>, fetch=<span class="italic">&lt;FETCH_TYPE&gt;</span>, 
    cascade=<span class="italic">&lt;CASCADE_TYPE&gt;</span>)

</pre>
<p>&nbsp;</p>
<img src="img/ngrelt.png" alt="Related task" title="Related task" /><br />
<br />
<a href="task_mapping.htm#BABDGBIJ">Mapping an entity</a>
<p>&nbsp;</p>
<img src="img/ngrelr.png" alt="Related reference" title="Related reference" /><br />
<br />
<a href="ref_persistence_outline.htm#BABEGGFE">JPA Structure view</a><br />
<a href="ref_persistence_map_view.htm#BABIFBAF">JPA Details view (for attributes)</a>
<p>&nbsp;</p>
<img src="img/ngrelc.png" alt="Related concept" title="Related concept" /><br />
<br />
<a href="concept_mapping.htm#BABBDJFI">Understanding OR mappings</a><br />
<a href="concepts001.htm#BABBGFJG">Understanding EJB 3.0 Java Persistence API</a></div>
<!-- class="sect2" -->
<!-- Start Footer -->
<div class="footer">
<table class="simple oac_no_warn" summary="" cellspacing="0" cellpadding="0" width="100%">
<tr>
<td align="left" width="86%"><a href="dcommon/html/cpyr.htm"><span class="copyrightlogo">Copyright&nbsp;&copy;&nbsp;2006, 2007,&nbsp;Oracle.&nbsp;All&nbsp;rights&nbsp;reserved.</span></a></td>
</tr>
</table>
</div>
<!-- class="footer" -->
</body>
</html>

Back to the top