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32            <h2 class="title" style="clear: both"><a id="ReplacingEntryWCursor"></a>Replacing Records Using Cursors</h2>
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36      <p>
37        You replace the data for a database record by using
38        
39
40        
41
42        <span>
43            <code class="methodname">DBC-&gt;put()</code>
44            
45            with the <code class="literal">DB_CURRENT</code> flag.
46        </span>
47            
48    </p>
49      <a id="c_cursor9"></a>
50      <pre class="programlisting">#include &lt;db.h&gt;
51#include &lt;string.h&gt;
52
53...
54
55DB *dbp;
56DBC *cursorp;
57DBT key, data;
58char *key1str = "My first string";
59char *replacement_data = "replace me";
60int ret;
61
62/* Initialize our DBTs. */
63memset(&amp;key, 0, sizeof(DBT));
64memset(&amp;data, 0, sizeof(DBT));
65
66/* Set up our DBTs */
67key.data = key1str;
68key.size = strlen(key1str) + 1;
69
70/* Database open omitted */
71
72/* Get the cursor */
73dbp-&gt;cursor(dbp, NULL, &amp;cursorp, 0);
74
75/* Position the cursor */
76ret = cursorp-&gt;get(cursorp, &amp;key, &amp;data, DB_SET);
77if (ret == 0) {
78    data.data = replacement_data;
79    data.size = strlen(replacement_data) + 1;
80    cursorp-&gt;put(cursorp, &amp;key, &amp;data, DB_CURRENT);
81}
82
83/* Cursors must be closed */
84if (cursorp != NULL) 
85    cursorp-&gt;close(cursorp); 
86
87if (dbp != NULL)
88    dbp-&gt;close(dbp, 0);</pre>
89      <p>
90        Note that you cannot change a record's key using this method; the key
91        parameter is always ignored when you replace a record.
92    </p>
93      <p>
94        When replacing the data portion of a record, if you are replacing a
95        record that is a member of a sorted duplicates set, then the replacement
96        will be successful only if the new record sorts identically to the old
97        record. This means that if you are replacing a record that is a member
98        of a sorted duplicates set, and if you are using the default
99        lexicographic sort, then the replacement will fail due to violating the
100        sort order. However, if you
101        provide a custom sort routine that, for example, sorts based on just a
102        few bytes out of the data item, then potentially you can perform
103        a direct replacement and still not violate the restrictions described
104        here.
105    </p>
106      <p>
107            <span>Under these circumstances, if</span>
108            
109        you want to replace the data contained by a duplicate record, 
110            <span>
111                and you are not using a custom sort routine, then
112            </span>
113        delete the record and create a new record with the desired key and data.
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