A more complex schema based on a call center example, showing how to map some SQL constructs onto the WiredTiger API.
/*-
 * Copyright (c) 2008-2012 WiredTiger, Inc.
 *
 * This is free and unencumbered software released into the public domain.
 *
 * Anyone is free to copy, modify, publish, use, compile, sell, or
 * distribute this software, either in source code form or as a compiled
 * binary, for any purpose, commercial or non-commercial, and by any
 * means.
 *
 * In jurisdictions that recognize copyright laws, the author or authors
 * of this software dedicate any and all copyright interest in the
 * software to the public domain. We make this dedication for the benefit
 * of the public at large and to the detriment of our heirs and
 * successors. We intend this dedication to be an overt act of
 * relinquishment in perpetuity of all present and future rights to this
 * software under copyright law.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * ex_call_center.c
 *      This is an example application that demonstrates how to map a
 *      moderately complex SQL application into WiredTiger.
 */

#include <inttypes.h>
#include <stdio.h>
#include <string.h>

#include <wiredtiger.h>

const char *home = "WT_TEST";

/*
 * In SQL, the tables are described as follows:
 *
 * CREATE TABLE Customers(id INTEGER PRIMARY KEY,
 *     name VARCHAR(30), address VARCHAR(50), phone VARCHAR(15))
 * CREATE INDEX CustomersPhone ON Customers(phone)
 *
 * CREATE TABLE Calls(id INTEGER PRIMARY KEY, call_date DATE,
 *     cust_id INTEGER, emp_id INTEGER, call_type VARCHAR(12),
 *     notes VARCHAR(25))
 * CREATE INDEX CallsCustDate ON Calls(cust_id, call_date)
 *
 * In this example, both tables will use record numbers for their IDs, which
 * will be the key.  The C structs for the records are as follows.
 */

/* Customer records. */
typedef struct {
        uint64_t id;
        char *name;
        char *address;
        char *phone;
} CUSTOMER;

/* Call records. */
typedef struct {
        uint64_t id;
        uint64_t call_date;
        uint64_t cust_id;
        uint64_t emp_id;
        char *call_type;
        char *notes;
} CALL;
int main(void)
{
        int count, exact, ret;
        WT_CONNECTION *conn;
        WT_SESSION *session;
        WT_CURSOR *cursor;
        CUSTOMER cust;
        CALL call;

        ret = wiredtiger_open(home, NULL, "create", &conn);
        if (ret != 0) {
                fprintf(stderr, "Error connecting to %s: %s\n",
                    home, wiredtiger_strerror(ret));
                return (1);
        }
        /* Note: further error checking omitted for clarity. */

        ret = conn->open_session(conn, NULL, NULL, &session);

        /*
         * Create the customers table, give names and types to the columns.
         * The columns will be stored in two groups: "main" and "address",
         * created below.
         */
        ret = session->create(session, "table:customers",
            "key_format=S,"
            "value_format=SSS,"
            "columns=(id,name,address,phone),"
            "colgroups=(main,address)");

        /* Create the main column group with value columns except address. */
        ret = session->create(session,
            "colgroup:customers:main", "columns=(name,phone)");

        /* Create the address column group with just the address. */
        ret = session->create(session,
            "colgroup:customers:address", "columns=(address)");

        /* Create an index on the customer table by phone number. */
        ret = session->create(session,
            "index:customers:phone", "columns=(phone)");

        /*
         * Create the calls table, give names and types to the columns.
         * All of the columns will be stored together, so no column groups are
         * declared.
         */
        ret = session->create(session, "table:calls",
            "key_format=r,"
            "value_format=qrrSS,"
            "columns=(id,call_date,cust_id,emp_id,call_type,notes)");

        /*
         * Create an index on the calls table with a composite key of cust_id
         * and call_date.
         */
        ret = session->create(session, "index:calls:cust_date",
            "columns=(cust_id,call_date)");

        /* Populate the customers table with some data. */
        ret = session->open_cursor(
            session, "table:customers", NULL, NULL, &cursor);

        cursor->set_key(cursor, "customer #1");
        cursor->set_value(cursor,
            "Professor Oak", "LeafGreen Avenue", "123-456-7890");
        ret = cursor->insert(cursor);

        cursor->set_key(cursor, "customer #2");
        cursor->set_value(cursor, "Lorelei", "Sevii Islands", "098-765-4321");
        ret = cursor->insert(cursor);

        ret = cursor->close(cursor);

        /*
         * First query: a call arrives.  In SQL:
         *
         * SELECT id, name FROM Customers WHERE phone=?
         *
         * Use the cust_phone index, lookup by phone number to fill the
         * customer record.  The cursor will have a key format of "S" for a
         * string because the cust_phone index has a single column ("phone"),
         * which is of type "S".
         *
         * Specify the columns we want: the customer ID and the name.  This
         * means the cursor's value format will be "rS".
         */
        ret = session->open_cursor(session,
            "index:customers:phone(id,name)",
            NULL, NULL, &cursor);
        cursor->set_key(cursor, "212-555-1000");
        ret = cursor->search(cursor);
        if (ret == 0) {
                ret = cursor->get_value(cursor, &cust.id, &cust.name);
                printf("Got customer record for %s\n", cust.name);
        }
        ret = cursor->close(cursor);

        /*
         * Next query: get the recent order history.  In SQL:
         *
         * SELECT * FROM Calls WHERE cust_id=? ORDER BY call_date DESC LIMIT 3
         *
         * Use the call_cust_date index to find the matching calls.  Since it is
         * is in increasing order by date for a given customer, we want to start
         * with the last record for the customer and work backwards.
         *
         * Specify a subset of columns to be returned.  If these were all
         * covered by the index, the primary would not be accessed.  Stop after
         * getting 3 records.
         */
        ret = session->open_cursor(session,
            "index:calls:cust_date(cust_id,call_type,notes)",
            NULL, NULL, &cursor);

        /*
         * The keys in the index are (cust_id,call_date) -- we want the largest
         * call date for a given cust_id.  Search for (cust_id+1,0), then work
         * backwards.
         */
        cursor->set_key(cursor, cust.id + 1, 0);
        ret = cursor->search_near(cursor, &exact);

        /*
         * If the table is empty, search_near will return WT_NOTFOUND.
         * Otherwise the cursor will on a matching key if one exists, or on an
         * adjacent key.  If the key we find is equal or larger than the search
         * key, go back one.
         */
        if (ret == 0 && exact >= 0)
                ret = cursor->prev(cursor);
        if (ret == 0)
                ret = cursor->get_value(cursor,
                    &call.cust_id, &call.call_type, &call.notes);

        count = 0;
        while (ret == 0 && call.cust_id == cust.id) {
                printf("Got call record on date %lu: type %s: %s\n",
                    (unsigned long)call.call_date, call.call_type, call.notes);
                if (++count == 3)
                        break;

                ret = cursor->prev(cursor);
                ret = cursor->get_value(cursor,
                    &call.cust_id, &call.call_type, &call.notes);
        }
        ret = conn->close(conn, NULL);

        return (ret);
}