1<?xml version="1.0" encoding="UTF-8" standalone="no"?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml"> 4 <head> 5 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> 6 <title>Deleting Secondary Database Records</title> 7 <link rel="stylesheet" href="gettingStarted.css" type="text/css" /> 8 <meta name="generator" content="DocBook XSL Stylesheets V1.62.4" /> 9 <link rel="home" href="index.html" title="Getting Started with Berkeley DB" /> 10 <link rel="up" href="indexes.html" title="Chapter��10.��Secondary Databases" /> 11 <link rel="previous" href="readSecondary.html" title="Reading Secondary Databases" /> 12 <link rel="next" href="secondaryCursor.html" title=" Using Secondary Cursors " /> 13 </head> 14 <body> 15 <div class="navheader"> 16 <table width="100%" summary="Navigation header"> 17 <tr> 18 <th colspan="3" align="center">Deleting Secondary Database Records</th> 19 </tr> 20 <tr> 21 <td width="20%" align="left"><a accesskey="p" href="readSecondary.html">Prev</a>��</td> 22 <th width="60%" align="center">Chapter��10.��Secondary Databases</th> 23 <td width="20%" align="right">��<a accesskey="n" href="secondaryCursor.html">Next</a></td> 24 </tr> 25 </table> 26 <hr /> 27 </div> 28 <div class="sect1" lang="en" xml:lang="en"> 29 <div class="titlepage"> 30 <div> 31 <div> 32 <h2 class="title" style="clear: both"><a id="secondaryDelete"></a>Deleting Secondary Database Records</h2> 33 </div> 34 </div> 35 <div></div> 36 </div> 37 <p> 38 In general, you 39 40 <span>will</span> 41 not modify a secondary database directly. In 42 order to modify a secondary database, you should modify the primary 43 database and simply allow DB to manage the secondary modifications for you. 44 </p> 45 <p> 46 However, as a convenience, you can delete 47 <tt class="classname">SecondaryDatabase</tt> 48 49 records directly. Doing so causes the associated primary key/data pair to be deleted. 50 This in turn causes DB to delete all 51 <tt class="classname">SecondaryDatabase</tt> 52 53 records that reference the primary record. 54 </p> 55 <p> 56 You can use the 57 <tt class="methodname">SecondaryDatabase.delete()</tt> 58 59 60 method to delete a secondary database record. 61 62 63 64 <span>Note that if your 65 66 <tt class="classname">SecondaryDatabase</tt> 67 contains duplicate records, then deleting a record from the set of 68 duplicates causes all of the duplicates to be deleted as well. 69 </span> 70 71 </p> 72 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> 73 <h3 class="title">Note</h3> 74 <p> 75 <span><tt class="methodname">SecondaryDatabase.delete()</tt> causes the 76 previously described delete operations to occur 77 </span> 78 79 only if the primary database is opened for write access. 80 </p> 81 </div> 82 <p>For example:</p> 83 <a id="java_index7"></a> 84 <pre class="programlisting">package db.GettingStarted; 85 86import com.sleepycat.db.DatabaseEntry; 87import com.sleepycat.db.DatabaseException; 88import com.sleepycat.db.OperationStatus; 89import com.sleepycat.db.SecondaryDatabase; 90 91... 92try { 93 SecondaryDatabase mySecondaryDatabase = null; 94 // Omitting all database opens 95 ... 96 97 String searchName = "John Doe"; 98 DatabaseEntry searchKey = 99 new DatabaseEntry(searchName.getBytes("UTF-8")); 100 101 // Delete the first secondary record that uses "John Doe" as 102 // a key. This causes the primary record referenced by this secondary 103 // record to be deleted. 104 OperationStatus retVal = mySecondaryDatabase.delete(null, searchKey); 105} catch (Exception e) { 106 // Exception handling goes here 107}</pre> 108 </div> 109 <div class="navfooter"> 110 <hr /> 111 <table width="100%" summary="Navigation footer"> 112 <tr> 113 <td width="40%" align="left"><a accesskey="p" href="readSecondary.html">Prev</a>��</td> 114 <td width="20%" align="center"> 115 <a accesskey="u" href="indexes.html">Up</a> 116 </td> 117 <td width="40%" align="right">��<a accesskey="n" href="secondaryCursor.html">Next</a></td> 118 </tr> 119 <tr> 120 <td width="40%" align="left" valign="top">Reading Secondary Databases��</td> 121 <td width="20%" align="center"> 122 <a accesskey="h" href="index.html">Home</a> 123 </td> 124 <td width="40%" align="right" valign="top">�� 125 Using Secondary Cursors 126 127 </td> 128 </tr> 129 </table> 130 </div> 131 </body> 132</html> 133