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<h1>Create one-to-many mappings</h1>
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<p>Use a <span class="bold">One-to-Many Mapping</span> to define a relationship from an attribute to another class, with one-to-many multiplicity to a database column. In the <a href="getting_started006.htm#BABIDCBA">Tutorial Object Model</a>, the <span class="bold">phoneNumbers</span> field of the <span class="bold">Employee</span> class has a one-to-many relationship to the <span class="bold">Phone</span> class; each employee may have many phone numbers.</p>
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<p>Select the <span class="bold">Employee</span> entity in the Package Explorer view.</p>
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<p>In the <a href="ref_persistence_outline.htm#BABEGGFE">JPA Structure view</a>, select the <span class="bold">phoneNumber</span> field of the <span class="bold">Employee</span> entity. The <a href="ref_persistence_map_view.htm#BABIFBAF">JPA Details view (for attributes)</a> displays the properties for the field.</p>
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<p>In the <span class="gui-object-title">Map As</span> field, select <span class="gui-object-action">One-to-Many</span>.</p>
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<p class="titleinfigure">One-to-many Mapping for phoneNumbers</p>
<img src="img/persistence_view_onetomany.png" alt="JPA Details view for the phoneNumbers field." title="JPA Details view for the phoneNumbers field." /><br /></div>
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<p>Select <span class="bold">PhoneNumber</span> as the Target Entity. Leave the other fields with their default values.</p>
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<p>In the Join Table area, notice that Dali has selected the correct joins, based on the foreign key associations in the database tables.</p>
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<p>In the JPA Structure, the <span class="bold">phoneNumbers</span> field is identified as a one-to-many mapping as shown in the following figure:</p>
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<p class="titleinfigure">JPA Structure for Employee Entity</p>
<img src="img/persistence_outline_phone.png" alt="The phoneNumbers attribute of the Employee entity in the JPA Structure view." title="The phoneNumbers attribute of the Employee entity in the JPA Structure view." /><br /></div>
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<p>Next, you will <a href="getting_started018.htm#BABCHIHI">Create many-to-one mappings</a>.</p>
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