Mysql C API的支持多查询执行实例

时间：2010-05-19 来源：admin126com

默认情况下，请求mysql_query（）和mysql_real_query（）解释为一个单一的声明中作出的声明字符串参数执行，并根据您处理结果是否语句产生一个结果集（一组行，至于选择）或受影响行数(INSERT，UPDATE,DELETE)。 /* connect to server with the CLIENT_MULTI_STATEMENTS option */
if (mysql_real_connect (mysql, host_name, user_name, password,
    db_name, port_num, socket_name, CLIENT_MULTI_STATEMENTS) == NULL)
{
printf("mysql_real_connect() failed\n");
mysql_close(mysql);
exit(1);
}

/* execute multiple statements */
status = mysql_query(mysql,
                     "DROP TABLE IF EXISTS test_table;\
                      CREATE TABLE test_table(id INT);\
                      INSERT INTO test_table VALUES(10);\
                      UPDATE test_table SET id=20 WHERE id=10;\
                      SELECT * FROM test_table;\
                      DROP TABLE test_table");
if (status)
{
printf("Could not execute statement(s)");
mysql_close(mysql);
exit(0);
}

/* process each statement result */
do {
/* did current statement return data? */
result = mysql_store_result(mysql);
if (result)
{
    /* yes; process rows and free the result set */
    process_result_set(mysql, result);
    mysql_free_result(result);
}
else          /* no result set or error */
{
    if (mysql_field_count(mysql) == 0)
    {
      printf("%lld rows affected\n",
            mysql_affected_rows(mysql));
    }
    else /* some error occurred */
    {
      printf("Could not retrieve result set\n");
      break;
    }
}
/* more results? -1 = no, >0 = error, 0 = yes (keep looping) */
if ((status = mysql_next_result(mysql)) > 0)
    printf("Could not execute statement\n");
} while (status == 0);

mysql_close(mysql);