To iterate over database records, from the first record to
        the last, simply open the cursor and then use the
            
            
            Dbc::get()
        method.  
        Note that you need to supply the
        DB_NEXT flag to this method.
        For example:
     
#include <db_cxx.h>
...
Db my_database(NULL, 0);
Dbc *cursorp;
try {
    // Database open omitted for clarity
    // Get a cursor
    my_database.cursor(NULL, &cursorp, 0); 
    Dbt key, data;
    int ret;
    // Iterate over the database, retrieving each record in turn.
    while ((ret = cursorp->get(&key, &data, DB_NEXT)) == 0) {
        // Do interesting things with the Dbts here.
    }
    if (ret != DB_NOTFOUND) {
        // ret should be DB_NOTFOUND upon exiting the loop.
        // Dbc::get() will by default throw an exception if any
        // significant errors occur, so by default this if block
        // can never be reached. 
    }
} catch(DbException &e) {
        my_database.err(e.get_errno(), "Error!");
} catch(std::exception &e) {
        my_database.errx("Error! %s", e.what());
}
// Cursors must be closed
if (cursorp != NULL) 
    cursorp->close(); 
my_database.close(0);
      
        To iterate over the database from the last record to the first, use 
        DB_PREV instead of DB_NEXT:
    
#include <db_cxx.h>
...
Db my_database(NULL, 0);
Dbc *cursorp;
try {
    // Database open omitted for clarity
    // Get a cursor
    my_database.cursor(NULL, &cursorp, 0); 
    Dbt key, data;
    int ret;
    // Iterate over the database, retrieving each record in turn.
    while ((ret = cursorp->get(&key, &data, DB_PREV)) == 0) {
        // Do interesting things with the Dbts here.
    }
    if (ret != DB_NOTFOUND) {
        // ret should be DB_NOTFOUND upon exiting the loop.
        // Dbc::get() will by default throw an exception if any
        // significant errors occur, so by default this if block
        // can never be reached. 
    }
} catch(DbException &e) {
        my_database.err(e.get_errno(), "Error!");
} catch(std::exception &e) {
        my_database.errx("Error! %s", e.what());
}
// Cursors must be closed
if (cursorp != NULL) 
    cursorp->close(); 
my_database.close(0);
      You can use cursors to search for database records. You can search based on just a key, or you can search based on both the key and the data. You can also perform partial matches if your database supports sorted duplicate sets. In all cases, the key and data parameters of these methods are filled with the key and data values of the database record to which the cursor is positioned as a result of the search.
        Also, if the search fails, then cursor's state is left unchanged
        and 
             
            DB_NOTFOUND 
        is returned. 
        
        
      
        To use a cursor to search for a record, use
            
            Dbt::get().
        When you use this method, you can provide the following flags:
    
            Notice in the following list that the cursor flags use the 
            keyword SET when the cursor examines just the key
            portion of the records (in this case, the cursor is set to the
            record whose key matches the value provided to the cursor).
            Moreover, when the cursor uses the keyword GET,
            then the cursor is positioned to both the key
            and the data values provided to the cursor.
        
            Regardless of the keyword you use to get a record with a cursor, the
            cursor's key and data 
                
                Dbts
            are filled with the data retrieved from the record to which the
            cursor is positioned.
        
            
            DB_SET
           
Moves the cursor to the first record in the database with the specified key.
            
            DB_SET_RANGE
          
            Identical to 
                DB_SET
                
            unless you are using the BTree access. In this case, the cursor
            moves
            
            
            to the first record in the database whose
            key is greater than or equal to the specified key. This comparison
            is determined by the 
                 
                comparison function 
            that you provide for the database. If no 
                 
                comparison function 
                is provided, then the default 
                
                lexicographical sorting is used.
          
For example, suppose you have database records that use the following Strings as keys:
Alabama Alaska Arizona
            Then providing a search key of Alaska moves the
            cursor to the second key noted above. Providing a key of
            Al moves the cursor to the first key (Alabama), providing
            a search key of Alas moves the cursor to the second key
            (Alaska), and providing a key of Ar moves the
            cursor to the last key (Arizona).
          
            
            DB_GET_BOTH
           
Moves the cursor to the first record in the database that uses the specified key and data.
            
            DB_GET_BOTH_RANGE
          
Moves the cursor to the first record in the database whose key matches the specified key and whose data is greater than or equal to the specified data. If the database supports duplicate records, then on matching the key, the cursor is moved to the duplicate record with the smallest data that is greater than or equal to the specified data.
For example, suppose your database uses BTree and it has database records that use the following key/data pairs:
Alabama/Athens Alabama/Florence Alaska/Anchorage Alaska/Fairbanks Arizona/Avondale Arizona/Florence
then providing:
| a search key of ... | and a search data of ... | moves the cursor to ... | 
|---|---|---|
| Alaska | Fa | Alaska/Fairbanks | 
| Arizona | Fl | Arizona/Florence | 
| Alaska | An | Alaska/Anchorage | 
For example, assuming a database containing sorted duplicate records of U.S. States/U.S Cities key/data pairs (both as Strings), then the following code fragment can be used to position the cursor to any record in the database and print its key/data values:
#include <db_cxx.h>
#include <string.h>
...
Db my_database(NULL, 0);
Dbc *cursorp;
try {
    // database open omitted for clarity
    // Get a cursor
    my_database.cursor(NULL, &cursorp, 0);
    // Search criteria
    char *search_key = "Alaska";
    char *search_data = "Fa";
    // Set up our DBTs
    Dbt key(search_key, strlen(search_key) + 1);
    Dbt data(search_data, strlen(search_data) + 1);
    // Position the cursor to the first record in the database whose
    // key matches the search key and whose data begins with the search
    // data.
    int ret = cursorp->get(&key, &data, DB_GET_BOTH_RANGE);
    if (!ret) {
        // Do something with the data
    }
} catch(DbException &e) {
        my_database.err(e.get_errno(), "Error!");
} catch(std::exception &e) {
        my_database.errx("Error! %s", e.what());
}
// Close the cursor
if (cursorp != NULL)
    cursorp->close();
// Close the database
my_database.close(0); 
      A record is a duplicate of another record if the two records share the same key. For duplicate records, only the data portion of the record is unique.
Duplicate records are supported only for the BTree or Hash access methods. For information on configuring your database to use duplicate records, see Allowing Duplicate Records.
		If your database supports duplicate records, then it can potentially
		contain multiple records that share the same key. 
        
        
        
        By default, normal database
		get operations will only return the first such record in a set
		of duplicate records. Typically, subsequent duplicate records are
        accessed using a cursor.
        
        The following 
            
            
            Dbc::get() flags
        are interesting when working with databases that support duplicate records:
	  
            
            
                DB_NEXT,
                DB_PREV
            
          
Shows the next/previous record in the database, regardless of whether it is a duplicate of the current record. For an example of using these methods, see Getting Records Using the Cursor.
            
            DB_GET_BOTH_RANGE
          
Useful for seeking the cursor to a specific record, regardless of whether it is a duplicate record. See Searching for Records for more information.
            
            
                DB_NEXT_NODUP,
                DB_PREV_NODUP
            
          
            Gets the next/previous non-duplicate record in the database.  This
            allows you to skip over all the duplicates in a set of duplicate
            records. If you call 
                 
                
                     
                    Dbc::get() 
                    with DB_PREV_NODUP,
                 
            then the cursor is positioned to the last record for the previous
            key in the database.  For example, if you have the following records
            in your database:
          
Alabama/Athens Alabama/Florence Alaska/Anchorage Alaska/Fairbanks Arizona/Avondale Arizona/Florence
          and your cursor is positioned to Alaska/Fairbanks,
          and you then call 
                 
                
                         
                    Dbc::get() 
                    with DB_PREV_NODUP,
                 
          then the cursor is positioned to Alabama/Florence. Similarly, if
          you call 
                 
                
                     
                    Dbc::get() 
                    with DB_NEXT_NODUP,
                 
            
          then the cursor is positioned to the first record corresponding to 
          the next key in the database.
          
            If there is no next/previous key in the database, then
                 
                DB_NOTFOUND 
            is returned, and the cursor is left unchanged.
          
            
                DB_NEXT_DUP
          
            Gets the 
                 
                next 
            record that shares the current key. If the
            cursor is positioned at the last record in the duplicate set and
            you call 
                 
                
                     
                    Dbc::get() 
                   with DB_NEXT_DUP,
                 
            then 
                 
                DB_NOTFOUND 
            is returned and the cursor is left unchanged. 
            
          
For example, the following code fragment positions a cursor to a key and displays it and all its duplicates.
#include <db_cxx.h>
#include <string.h>
...
char *search_key = "Al";
Db my_database(NULL, 0);
Dbc *cursorp;
try {
    // database open omitted for clarity
    // Get a cursor
    my_database.cursor(NULL, &cursorp, 0);
    // Set up our DBTs
    Dbt key(search_key, strlen(search_key) + 1);
    Dbt data;
    // Position the cursor to the first record in the database whose
    // key and data begin with the correct strings.
    int ret = cursorp->get(&key, &data, DB_SET);
    while (ret != DB_NOTFOUND) {
        std::cout << "key: " << (char *)key.get_data() 
                  << "data: " << (char *)data.get_data()<< std::endl;
        ret = cursorp->get(&key, &data, DB_NEXT_DUP);
    }
} catch(DbException &e) {
        my_database.err(e.get_errno(), "Error!");
} catch(std::exception &e) {
        my_database.errx("Error! %s", e.what());
}
// Close the cursor
if (cursorp != NULL)
    cursorp->close();
// Close the database
my_database.close(0);