MySQL in a Nutshell, 2nd Edition

Name

mysql_use_result()

Synopsis

MYSQL_RES *mysql_use_result(MYSQL *mysql)

Use this function to read the results of a query, one row at a time. This works in a way similar to the mysql_store_result() function, except that function retrieves all of the data at once and stores it for later use. The mysql_use_result() function is best used when a results set would be large and speed of processing is a concern. With this function, processing may be started sooner without having to wait for all of the data to be retrieved. One drawback to this function is that other queries cannot be run while the results from the first query are in use. Also, functions such as mysql_data_seek() cannot be used and the return value from running mysql_num_rows() is altered, because the complete size of the results set is unknown. Here is an example:

...
mysql_query(mysql, "SELECT * FROM clients");
result = mysql_use_result(mysql);
num_fields = mysql_field_count(mysql);
while((row = mysql_fetch_row(result)) != NULL)
   {
    for(i = 0; i < num_fields; i++)
      {
       field = mysql_fetch_field_direct(result, i);
       printf("%s: %s, ", field->name, row[i]);
      }
   printf("\n");
}
mysql_free_result(result);
...

See the example for the mysql_fetch_row() function earlier in this chapter for an alternative method.