Library Version 11.2.5.2

Using Cursors with Secondary Databases
Prev | Chapter 5. Secondary Databases | Next

## Using Cursors with Secondary Databases

Just like cursors on a primary database, you can use cursors on secondary databases to iterate over the records in a secondary database. Like cursors used with primary databases, you can also use cursors with secondary databases to search for specific records in a database, to seek to the first or last record in the database, to get the next duplicate record, and so forth. For a complete description on cursors and their capabilities, see Using Cursors.

However, when you use cursors with secondary databases:

- Any data returned is the data contained on the primary database record referenced by the secondary record.

- You cannot use `DB_GET_BOTH` and related flags with `Db::get()` and a secondary database. Instead, you must use `Db::pget()`. Also, in that case the primary and secondary key given on the call to `Db::pget()` must match the secondary key and associated primary record key in order for that primary record to be returned as a result of the call.

For example, suppose you are using the databases, classes, and key extractors described in Implementing Key Extractors . Then the following searches for a person's name in the secondary database, and deletes all secondary and primary records that use that name.

    #include <db_cxx.h>

    ...

    Db my_database(NULL, 0);
    Db my_index(NULL, 0);

    // Get a cursor on the secondary database
    Dbc *cursorp;
    my_index.cursor(NULL, &cursorp, 0);

    // Name to delete
    char *search_name = "John Doe";

    // Instantiate Dbts as normal
    Dbt key(search_name, strlen(search_name) + 1);
    Dbt data;

    // Position the cursor
    while (cursorp->get(&key, &data, DB_SET) == 0)
        cursorp->del(0);

Prev | Up | Next
Deleting Secondary Database Records | Home | Database Joins