/* mult_update.c:  test multi-statement update
 *
 * This program demonstrates two things:
 * - If mysql_next_result() isn't called after a multi-statement query, there
 *   will be a protocol error (feature request)
 * - But if sleep(1) is called between the two mysql_query() calls, then the
 *   protocol error goes away (bug - why does this happen?)
 *
 * Create a table in the 'test' database as follows:

drop table if exists test.mult_update;
create table test.mult_update (f1 int, f2 varchar(100), f3 varchar(100));
insert into test.mult_update (f1, f2, f3) values
    (0, "f2 0", "f3 0"), (1, "f2 1", "f3 1");

 * Then run this program to test.
*/

/* If mysql_next_result() is called, the program works fine */
#define CALL_MYSQL_NEXT_RESULT 0

/* If sleep(1) is called, the program seems to work fine */
#define SLEEP_HACK 0


#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <mysql.h>

MYSQL *dbh;
MYSQL_RES *results;
MYSQL_ROW record;

void _die (int line, const char *msg)
{
    fprintf(stderr, "Program terminated at line %d: %s\n", line, msg);
    exit(EXIT_FAILURE);
}
#define die(msg) _die(__LINE__, (msg))

int main(void)
{
    int i;
    int rc;

    /* Connect to server */
    dbh = mysql_init(NULL);
    if (!dbh)
        die("mysql_init() failed");
    mysql_options(dbh, MYSQL_READ_DEFAULT_GROUP, "client");
    if (mysql_real_connect(dbh, NULL, NULL, NULL,
                "test", 0, NULL, CLIENT_MULTI_STATEMENTS) == NULL)
        die(mysql_error(dbh));

    /* Do multi-statement updates, in a loop */
    for (i = 0; i < 2; ++i)
    {
        char buf[300];
        snprintf(buf, sizeof(buf), "update mult_update set f2 = 'test f2 %d' where f1 = '%d'; update mult_update set f3 = 'test f3 %d' where f1 = %d", i, i, i, i);

        printf("iter %d: buf: '%s'\n", i, buf);

        if (mysql_query(dbh, buf) != 0)
            die(mysql_error(dbh));

        do
        {
            printf("\t- A statement affected %llu row(s)\n",
                    mysql_affected_rows(dbh));
#if SLEEP_HACK
            /* For some reason, this makes things "work" ok */
            fprintf(stderr, "Sleeping for 1 second...\n");
            sleep(1);
#endif
        }
#if CALL_MYSQL_NEXT_RESULT
        while ((rc = mysql_next_result(dbh)) == 0);

        if (rc > 0)
            die(mysql_error(dbh));
#else
        while (0);
#endif
    }
    mysql_close(dbh);

    exit(EXIT_SUCCESS);
}