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HTML
252 lines
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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>Using Entities with Collections</title>
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<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
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<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
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<link rel="start" href="index.html" title="Berkeley DB Collections Tutorial" />
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<link rel="up" href="Entity.html" title="Chapter 4. Using Entity Classes" />
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<link rel="prev" href="collectionswithentities.html" title="Creating Collections with Entity Bindings" />
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<link rel="next" href="Tuple.html" title="Chapter 5. Using Tuples" />
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</head>
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<body>
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<div xmlns="" class="navheader">
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<div class="libver">
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<p>Library Version 11.2.5.2</p>
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</div>
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<table width="100%" summary="Navigation header">
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<tr>
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<th colspan="3" align="center">
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Using Entities with Collections
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</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="collectionswithentities.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 4.
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Using Entity Classes
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</th>
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<td width="20%" align="right"> <a accesskey="n" href="Tuple.html">Next</a></td>
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</tr>
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</table>
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<hr />
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</div>
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<div class="sect1" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h2 class="title" style="clear: both"><a id="entitieswithcollections"></a>
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Using Entities with Collections
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</h2>
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</div>
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</div>
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</div>
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<p>
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In this example entity objects, rather than key and value
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objects, are used for adding and enumerating the records in a
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collection. Because fewer classes and objects are involved, adding
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and enumerating is done more conveniently and more simply than in
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the prior examples.
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</p>
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<p>
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For adding and iterating entities, the collection of entities
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returned by
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<a class="ulink" href="http://download.oracle.com/javase/1.5.0/docs/api/java/util/Map.html#values()" target="_top">Map.values</a>
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is used. In general, when using an entity binding, all Java
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collection methods that are passed or returned a value object will
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be passed or returned an entity object instead.
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</p>
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<p>
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The <code class="classname">Sample</code> class has been changed in this example to add
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objects using the
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<a class="ulink" href="http://download.oracle.com/javase/1.5.0/docs/api/java/util/Set.html#add(E)" target="_top">Set.add</a>
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method rather than the
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<a class="ulink" href="http://download.oracle.com/javase/1.5.0/docs/api/java/util/Map.html#put(K, V)" target="_top">Map.put</a>
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method that was used in the prior examples. Entity objects are
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constructed and passed to
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<a class="ulink" href="http://download.oracle.com/javase/1.5.0/docs/api/java/util/Set.html#add(E)" target="_top">Set.add</a>.
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</p>
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<a id="entity_addsuppliers"></a>
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<pre class="programlisting">import java.util.Set;
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...
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public class Sample
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{
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...
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private void addSuppliers()
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{
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<strong class="userinput"><code> Set suppliers = views.getSupplierSet();
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if (suppliers.isEmpty())
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{
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System.out.println("Adding Suppliers");
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suppliers.add(new Supplier("S1", "Smith", 20, "London"));
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suppliers.add(new Supplier("S2", "Jones", 10, "Paris"));
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suppliers.add(new Supplier("S3", "Blake", 30, "Paris"));
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suppliers.add(new Supplier("S4", "Clark", 20, "London"));
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suppliers.add(new Supplier("S5", "Adams", 30, "Athens"));
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}</code></strong>
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}
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private void addParts()
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{
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<strong class="userinput"><code> Set parts = views.getPartSet();
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if (parts.isEmpty())
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{
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System.out.println("Adding Parts");
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parts.add(new Part("P1", "Nut", "Red",
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new Weight(12.0, Weight.GRAMS), "London"));
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parts.add(new Part("P2", "Bolt", "Green",
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new Weight(17.0, Weight.GRAMS), "Paris"));
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parts.add(new Part("P3", "Screw", "Blue",
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new Weight(17.0, Weight.GRAMS), "Rome"));
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parts.add(new Part("P4", "Screw", "Red",
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new Weight(14.0, Weight.GRAMS), "London"));
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parts.add(new Part("P5", "Cam", "Blue",
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new Weight(12.0, Weight.GRAMS), "Paris"));
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parts.add(new Part("P6", "Cog", "Red",
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new Weight(19.0, Weight.GRAMS), "London"));
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}</code></strong>
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}
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private void addShipments()
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{
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<strong class="userinput"><code> Set shipments = views.getShipmentSet();
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if (shipments.isEmpty())
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{
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System.out.println("Adding Shipments");
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shipments.add(new Shipment("P1", "S1", 300));
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shipments.add(new Shipment("P2", "S1", 200));
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shipments.add(new Shipment("P3", "S1", 400));
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shipments.add(new Shipment("P4", "S1", 200));
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shipments.add(new Shipment("P5", "S1", 100));
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shipments.add(new Shipment("P6", "S1", 100));
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shipments.add(new Shipment("P1", "S2", 300));
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shipments.add(new Shipment("P2", "S2", 400));
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shipments.add(new Shipment("P2", "S3", 200));
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shipments.add(new Shipment("P2", "S4", 200));
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shipments.add(new Shipment("P4", "S4", 300));
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shipments.add(new Shipment("P5", "S4", 400));
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}</code></strong>
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} </pre>
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<p>
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Instead of printing the key/value pairs by iterating over the
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<a class="ulink" href="http://download.oracle.com/javase/1.5.0/docs/api/java/util/Map.html#entrySet()" target="_top">Map.entrySet</a>
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as done in the prior example, this example
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iterates over the entities in the
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<a class="ulink" href="http://download.oracle.com/javase/1.5.0/docs/api/java/util/Map.html#values()" target="_top">Map.values</a>
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collection.
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</p>
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<a id="entity_printdatabase"></a>
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<pre class="programlisting">import java.util.Iterator;
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import java.util.Set;
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...
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public class Sample
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{
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...
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private class PrintDatabase implements TransactionWorker
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{
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public void doWork()
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throws Exception
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{
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<strong class="userinput"><code> printValues("Parts",
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views.getPartSet().iterator());
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printValues("Suppliers",
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views.getSupplierSet().iterator());</code></strong>
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printValues("Suppliers for City Paris",
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views.getSupplierByCityMap().duplicates(
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"Paris").iterator());
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<strong class="userinput"><code> printValues("Shipments",
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views.getShipmentSet().iterator());</code></strong>
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printValues("Shipments for Part P1",
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views.getShipmentByPartMap().duplicates(
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new PartKey("P1")).iterator());
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printValues("Shipments for Supplier S1",
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views.getShipmentBySupplierMap().duplicates(
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new SupplierKey("S1")).iterator());
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}
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}
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...
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} </pre>
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<p>
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The output of the example program is shown below.
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</p>
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<pre class="programlisting">Adding Suppliers
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Adding Parts
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Adding Shipments
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--- Parts ---
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Part: number=P1 name=Nut color=Red weight=[12.0 grams] city=London
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Part: number=P2 name=Bolt color=Green weight=[17.0 grams] city=Paris
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Part: number=P3 name=Screw color=Blue weight=[17.0 grams] city=Rome
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Part: number=P4 name=Screw color=Red weight=[14.0 grams] city=London
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Part: number=P5 name=Cam color=Blue weight=[12.0 grams] city=Paris
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Part: number=P6 name=Cog color=Red weight=[19.0 grams] city=London
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--- Suppliers ---
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Supplier: number=S1 name=Smith status=20 city=London
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Supplier: number=S2 name=Jones status=10 city=Paris
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Supplier: number=S3 name=Blake status=30 city=Paris
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Supplier: number=S4 name=Clark status=20 city=London
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Supplier: number=S5 name=Adams status=30 city=Athens
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--- Suppliers for City Paris ---
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Supplier: number=S2 name=Jones status=10 city=Paris
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Supplier: number=S3 name=Blake status=30 city=Paris
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--- Shipments ---
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Shipment: part=P1 supplier=S1 quantity=300
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Shipment: part=P1 supplier=S2 quantity=300
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Shipment: part=P2 supplier=S1 quantity=200
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Shipment: part=P2 supplier=S2 quantity=400
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Shipment: part=P2 supplier=S3 quantity=200
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Shipment: part=P2 supplier=S4 quantity=200
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Shipment: part=P3 supplier=S1 quantity=400
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Shipment: part=P4 supplier=S1 quantity=200
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Shipment: part=P4 supplier=S4 quantity=300
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Shipment: part=P5 supplier=S1 quantity=100
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Shipment: part=P5 supplier=S4 quantity=400
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Shipment: part=P6 supplier=S1 quantity=100
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--- Shipments for Part P1 ---
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Shipment: part=P1 supplier=S1 quantity=300
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Shipment: part=P1 supplier=S2 quantity=300
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--- Shipments for Supplier S1 ---
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Shipment: part=P1 supplier=S1 quantity=300
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Shipment: part=P2 supplier=S1 quantity=200
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Shipment: part=P3 supplier=S1 quantity=400
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Shipment: part=P4 supplier=S1 quantity=200
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Shipment: part=P5 supplier=S1 quantity=100
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Shipment: part=P6 supplier=S1 quantity=100 </pre>
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</div>
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<div class="navfooter">
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<hr />
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<table width="100%" summary="Navigation footer">
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<tr>
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<td width="40%" align="left"><a accesskey="p" href="collectionswithentities.html">Prev</a> </td>
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<td width="20%" align="center">
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|||
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<a accesskey="u" href="Entity.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="Tuple.html">Next</a></td>
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</tr>
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<tr>
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<td width="40%" align="left" valign="top">
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|
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Creating Collections with Entity Bindings
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</td>
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<td width="20%" align="center">
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<a accesskey="h" href="index.html">Home</a>
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</td>
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<td width="40%" align="right" valign="top"> Chapter 5.
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|||
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Using Tuples
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|||
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</td>
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</tr>
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</table>
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</div>
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</body>
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</html>
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