mysql_free_result( );

public OnPlayerConnect(playerid)
{
    mysql_format(dbHandle, query, sizeof(query), "SELECT * FROM `users` WHERE `username` = '%s' LIMIT 1", Player[playerid][Name]);
    mysql_tquery(dbHandle, query, "OnPlayerLoad", "i", playerid);
}

forward OnPlayerLoad(playerid);
public OnPlayerLoad(playerid)
{
    // cache_num_rows() returns whether there's been a result or not so you can do the following:
    if(cache_num_rows()) {
        // User exists
        // cache_get_field_content_int(0, "columnname"); = retrieves an INT value from the database
        // cache_get_field_content_float(0, "columnname"); = retrieves a FLOAT value from the database
        // cache_get_field_content(0, "columnname", destinationvar, dbHandle, maxsize); = retrieves a STRING from the database
    } else {
        // No user found in the database
    }
    return 1;
}

public OnGameModeInit()
{
    mysql_format(dbHandle, query, sizeof(query), "SELECT * FROM `vehicles` LIMIT %d", MAX_DYNAMIC_VEHS);
    mysql_tquery(dbHandle, query, "OnObjectsLoad");
}

forward OnObjectsLoad();
public OnObjectsLoad()
{
    // cache_num_rows() returns whether there's been a result or not so you can do the following:
    // Now we can run through a loop to retrieve all rows database

    for(new i = 0; i < cache_num_rows(); i++)
    {
        // Make sure you use the 'i' variable as it always incerements in the loop in order to read from the rows
        // User exists
        // cache_get_field_content_int(i, "columnname"); = retrieves an INT value from the database
        // cache_get_field_content_float(i, "columnname"); = retrieves a FLOAT value from the database
        // cache_get_field_content(i, "columnname", destinationvar, dbHandle, maxsize); = retrieves a STRING from the database
    }
    return 1;
}