Putting Records Using Cursors

You can use cursors to put records into the database. DB's behavior when putting records into the database differs depending on the flags that you use when writing the record, on the access method that you are using, and on whether your database supports sorted duplicates.

Note that when putting records to the database using a cursor, the cursor is positioned at the record you inserted.

You use DBC->put() to put (write) records to the database. You can use the following flags with this method:

For example:

#include <db.h>
#include <string.h>


DB *dbp;
DBC *cursorp;
DBT data1, data2, data3;
DBT key1, key2;
char *key1str = "My first string";
char *data1str = "My first data";
char *key2str = "A second string";
char *data2str = "My second data";
char *data3str = "My third data";
int ret;

/* Set up our DBTs */
key1.data = key1str;
key1.size = strlen(key1str) + 1;
data1.data = data1str;
data1.size = strlen(data1str) + 1;

key2.data = key2str;
key2.size = strlen(key2str) + 1;
data2.data = data2str;
data2.size = strlen(data2str) + 1;
data3.data = data3str;
data3.size = strlen(data3str) + 1;

/* Database open omitted */

/* Get the cursor */
dbp->cursor(dbp, NULL, &cursorp, 0);

 * Assuming an empty database, this first put places
 * "My first string"/"My first data" in the first 
 * position in the database
ret = cursorp->put(cursorp, &key1, 
  &data1, DB_KEYFIRST); 

 * This put places "A second string"/"My second data" in the
 * the database according to its key sorts against the key 
 * used for the currently existing database record. Most likely
 * this record would appear first in the database.
ret = cursorp->put(cursorp, &key2, 
  &data2, DB_KEYFIRST); /* Added according to sort order */

 * If duplicates are not allowed, the currently existing record that 
 * uses "key2" is overwritten with the data provided on this put.
 * That is, the record "A second string"/"My second data" becomes
 * "A second string"/"My third data"
 * If duplicates are allowed, then "My third data" is placed in the
 * duplicates list according to how it sorts against "My second data".
ret = cursorp->put(cursorp, &key2, 
  &data3, DB_KEYFIRST); /* If duplicates are not allowed, record 
                         * is overwritten with new data. Otherwise, 
                         * the record is added to the beginning of 
                         * the duplicates list.