003 File Manager
Current Path:
/usr/local/share/doc/db5/gsg/CXX
usr
/
local
/
share
/
doc
/
db5
/
gsg
/
CXX
/
📁
..
📄
BerkeleyDB-Core-Cxx-GSG.pdf
(402.24 KB)
📄
CoreCursorUsage.html
(11.1 KB)
📄
CoreDBAdmin.html
(5.22 KB)
📄
CoreDbCXXUsage.html
(7 KB)
📄
CoreEnvUsage.html
(6.97 KB)
📄
Cursors.html
(5.93 KB)
📄
DBEntry.html
(6.46 KB)
📄
DBOpenFlags.html
(4.32 KB)
📄
DbCXXUsage.html
(20.83 KB)
📄
DeleteEntryWCursor.html
(3.69 KB)
📄
Positioning.html
(19.87 KB)
📄
PutEntryWCursor.html
(8.37 KB)
📄
ReplacingEntryWCursor.html
(4.94 KB)
📄
accessmethods.html
(12.5 KB)
📄
btree.html
(21.41 KB)
📄
cachesize.html
(4.56 KB)
📄
concepts.html
(8.63 KB)
📄
coreExceptions.html
(3.78 KB)
📄
coredbclose.html
(4.33 KB)
📄
coreindexusage.html
(22.31 KB)
📄
databaseLimits.html
(3.77 KB)
📄
databases.html
(6.07 KB)
📄
dbErrorReporting.html
(7.36 KB)
📄
dbconfig.html
(17.69 KB)
📄
environments.html
(6.31 KB)
📄
gettingStarted.css
(1.13 KB)
📄
gettingit.html
(3.45 KB)
📄
index.html
(16.66 KB)
📄
indexes.html
(12.17 KB)
📄
introduction.html
(9.77 KB)
📄
joins.html
(10.09 KB)
📄
keyCreator.html
(10.23 KB)
📄
moreinfo.html
(6.97 KB)
📄
preface.html
(6.36 KB)
📄
readSecondary.html
(4.95 KB)
📄
returns.html
(3.52 KB)
📄
secondaryCursor.html
(5.34 KB)
📄
secondaryDelete.html
(5.79 KB)
📄
usingDbt.html
(15.18 KB)
Editing: readSecondary.html
<?xml version="1.0" encoding="UTF-8" standalone="no"?> <!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"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>Reading Secondary Databases</title> <link rel="stylesheet" href="gettingStarted.css" type="text/css" /> <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> <link rel="start" href="index.html" title="Getting Started with Berkeley DB" /> <link rel="up" href="indexes.html" title="Chapter 5. Secondary Databases" /> <link rel="prev" href="keyCreator.html" title="Implementing Key Extractors" /> <link rel="next" href="secondaryDelete.html" title="Deleting Secondary Database Records" /> </head> <body> <div xmlns="" class="navheader"> <div class="libver"> <p>Library Version 11.2.5.3</p> </div> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">Reading Secondary Databases</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="keyCreator.html">Prev</a> </td> <th width="60%" align="center">Chapter 5. Secondary Databases</th> <td width="20%" align="right"> <a accesskey="n" href="secondaryDelete.html">Next</a></td> </tr> </table> <hr /> </div> <div class="sect1" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h2 class="title" style="clear: both"><a id="readSecondary"></a>Reading Secondary Databases</h2> </div> </div> </div> <p> Like a primary database, you can read records from your secondary database either by using the <span> <code class="methodname">Db::get()</code> or <code class="methodname">Db::pget()</code> methods, </span> or by using <span>a cursor on the secondary database.</span> The main difference between reading secondary and primary databases is that when you read a secondary database record, the secondary record's data is not returned to you. Instead, the primary key and data corresponding to the secondary key are returned to you. </p> <p> For example, assuming your secondary database contains keys related to a person's full name: </p> <a id="cxx_index6"></a> <pre class="programlisting">#include <db_cxx.h> #include <string.h> ... // The string to search for char *search_name = "John Doe"; // Instantiate our Dbt's Dbt key(search_name, strlen(search_name) + 1); Dbt pkey, pdata; // Primary key and data Db my_secondary_database(NULL, 0); // Primary and secondary database opens omitted for brevity // Returns the key from the secondary database, and the data from the // associated primary database entry. my_secondary_database.get(NULL, &key, &pdata, 0); // Returns the key from the secondary database, and the key and data // from the associated primary database entry. my_secondary_database.pget(NULL, &key, &pkey, &pdata, 0);</pre> <p> Note that, just like <span>a primary database,</span> if your secondary database supports duplicate records then <span> <code class="methodname">Db::get()</code> and <code class="methodname">Db::pget()</code> </span> only return the first record found in a matching duplicates set. If you want to see all the records related to a specific secondary key, then use a <span> cursor opened on the secondary database. Cursors are described in <a class="xref" href="Cursors.html" title="Chapter 4. Using Cursors">Using Cursors</a>. </span> </p> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="keyCreator.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="indexes.html">Up</a> </td> <td width="40%" align="right"> <a accesskey="n" href="secondaryDelete.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">Implementing Key <span>Extractors</span> </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> Deleting Secondary Database Records</td> </tr> </table> </div> </body> </html>
Upload File
Create Folder