PHP / MySQL结合两个查询以减少循环

Question

I have the following query, whos results then loop out to run another query and retrieve another set of results, but I would like to combine these so I am not running so many queries and to speed everything up, but I've tried a few iterations and either get null results, or errors with the syntax. So looking for some community magic here.

Query 1:

SELECT tou_tracking_start, tou_tracking_end, tou_tracking_timestart,
tou_tracking_timeend, tou_tracking_units, daytype_ID 
FROM db_tou_tracking 
WHERE ICP_ID = '39' 
AND (tou_tracking_start >= '2013-01-01' AND tou_tracking_end <= '2013-12-31')

Which loops out its results and are then used in the next query:

SELECT rates_tou_rate, rates_tou_PPD FROM db_rates_tou 
WHERE (rates_tou_start <= '" .$tou_tracking_start . 
    "' AND rates_tou_end >= '" . $tou_tracking_end . "') 
AND (rates_tou_timestart <= '" . $tou_tracking_timestart . 
    "' AND rates_tou_timeend >= '" . $tou_tracking_timeend . "') 
AND daytype_ID = ".$tou_tracking_daytype_ID." 
LIMIT 1

If these can be combined, then I only need to select:

• tou_tracking_start
• tou_tracking_end
• rates_tou_rate
• rates_tou_PPD

Many thanks in advance for the help with this.

Answer 1

I would use a JOIN

SELECT tt.tou_tracking_start, tt.tou_tracking_end, rt.rates_tou_rate, rt.rates_tou_PPD
FROM db_tou_tracking tt
JOIN db_rates_tou rt ON rt.daytypeID = tt.daytype_ID
AND (tt.tou_tracking_start >= '2013-01-01' AND tt.tou_tracking_end <= '2013-12-31')

tt is an alias for db_tou_tracking and rt is an alias for db_rates_tou.

I assume they are matched by daytype_ID in both tables and there is a 1 to 1 relationship.