Skip to main content
summaryrefslogblamecommitdiffstats
blob: b7943aaab59d34cda73a5382cca190a235a3a2f9 (plain) (tree)
1
2
3
4
5
6
7
8
9
10



                                                                   
                                         
                                                                        

                                  

                                                                   
                                                                                              
                                                        
                                          


                                                                                                                                                                                                                                                                                                                                                                      

                                                                                               

                 

       
                                            
                                                              
                            
                                                                                                                                                                                                                                                                                                                        
              
    
                                                                                                             

     
                                                                                                                                                                                                                                   
     



















































































                                                                                                                                                                                                                                                                                                             
                                                                                                                                                                                                                                                      







                                                                                                           
     
                                                           
                                              



                                                                                                                                 



















                                                                                          
                                                                                                                                                                                                





                       
<!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 = July 23, 2008 8:59:47 -->
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii" />
<title>Many-to-one mapping</title>
 
<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 (Mode = ohj/ohw) - Version 5.0" />
<meta name="date" content="2005-07-10T12:57:20+08:00" />
<meta name="robots" content="noarchive" />
<meta name="doctitle" content="Many-to-one mapping" />
<meta name="relnum" content="Release 2.0" />
<meta name="copyright" content="Copyright (c) 2000, 2008 oracle . All rights reserved. This program and the accompanying materials are made available under the terms of the Eclipse Public License v1.0 which accompanies this distribution, and is available at http://www.eclipse.org/legal/epl-v10.html. Contributors: Oracle - initial API and implementation" />
<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" />
<!-- start-->
<!-- contents -->
</head>
<body>
<p><a id="BABHFAFJ" name="BABHFAFJ"></a></p>
<div class="sect2"><!-- infolevel="all" infotype="General" -->
<h1>Many-to-one mapping</h1>
<p><a id="sthref117" name="sthref117"></a><a id="sthref118" name="sthref118"></a><a id="sthref119" name="sthref119"></a><a id="sthref120" name="sthref120"></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 start="1">
<li>
<p>In the <a href="ref_persistence_outline.htm#BABEGGFE">JPA Structure view</a>, select the field to map.</p>
</li>
<li>
<p>Right click the field and then select <span class="bold">Map As &gt; Many-to-One</span>. 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>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-t22">Property</th>
<th align="left" valign="bottom" id="r1c2-t22">Description</th>
<th align="left" valign="bottom" id="r1c3-t22">Default</th>
</tr>
</thead>
<tbody>
<tr align="left" valign="top">
<td align="left" id="r2c1-t22" headers="r1c1-t22">Mapping Entity Hyperlink</td>
<td align="left" headers="r2c1-t22 r1c2-t22">Defines mapping as <span class="bold">Many-to-One</span>. This corresponds to the <code>@ManyToOne</code> annotation.</td>
<td align="left" headers="r2c1-t22 r1c3-t22">Many-to-One</td>
</tr>
<tr align="left" valign="top">
<td align="left" id="r3c1-t22" headers="r1c1-t22">Target Entity</td>
<td align="left" headers="r3c1-t22 r1c2-t22">The entity to which this attribute is mapped.</td>
<td align="left" headers="r3c1-t22 r1c3-t22">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="r4c1-t22" headers="r1c1-t22">Fetch</td>
<td align="left" headers="r4c1-t22 r1c2-t22">Defines how data is loaded from the database. See <a href="ref_mapping_general.htm#CACGGGHB">"Fetch Type"</a> for details.
<ul>
<li>
<p>Eager</p>
</li>
<li>
<p>Lazy</p>
</li>
</ul>
</td>
<td align="left" headers="r4c1-t22 r1c3-t22">Eager</td>
</tr>
<tr align="left" valign="top">
<td align="left" id="r5c1-t22" headers="r1c1-t22">Cascade</td>
<td align="left" headers="r5c1-t22 r1c2-t22">See <a href="ref_mapping_general.htm#CACJAIHB">"Cascade Type"</a> for details.
<ul>
<li>
<p>Default</p>
</li>
<li>
<p>All</p>
</li>
<li>
<p>Persist</p>
</li>
<li>
<p>Merge</p>
</li>
<li>
<p>Remove</p>
</li>
</ul>
</td>
<td align="left" headers="r5c1-t22 r1c3-t22">Default</td>
</tr>
<tr align="left" valign="top">
<td align="left" id="r6c1-t22" headers="r1c1-t22">Optional</td>
<td align="left" headers="r6c1-t22 r1c2-t22">Specifies if this field is can be null.</td>
<td align="left" headers="r6c1-t22 r1c3-t22">Yes</td>
</tr>
</tbody>
</table>
<br /></div>
<!-- class="inftblruleinformal" --></li>
<li>
<p>Use this table to complete the fields on the <a href="reference015.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-t23">Property</th>
<th align="left" valign="bottom" id="r1c2-t23">Description</th>
<th align="left" valign="bottom" id="r1c3-t23">Default</th>
</tr>
</thead>
<tbody>
<tr align="left" valign="top">
<td align="left" id="r2c1-t23" headers="r1c1-t23">Join Column</td>
<td align="left" headers="r2c1-t23 r1c2-t23"><a id="sthref121" name="sthref121"></a><a id="sthref122" name="sthref122"></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-t23 r1c3-t23">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, 2008,&nbsp;Oracle.&nbsp;All&nbsp;rights&nbsp;reserved.</span></a></td>
</tr>
</table>
</div>
<!-- class="footer" -->
</body>
</html>

Back to the top