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POMore efficient way to do SQL queries
 

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  1. POMore efficient way to do SQL queries
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    <p>I've been using the below php and sql for loading schedule information and real time information for passenger trains in the UK. Essentially you have to find the relevant schedules, and then load the realtime information for each schedule which is in a different table relating to todays trains.</p> <p>The query is taking a little longer than is really idea and using lots of CPU% which again isn''t ideal. I'm pretty weak when it comes to sql programming so any pointers as to what is inefficient would be great.</p> <p>This is for an android app and so i've tried to all with one call over http. The prints(*) and > is for splitting the string at the other end. </p> <p>Here is the code:</p> <pre><code>&lt;? //Connect to the database mysql_connect("localhost","XXXX","XXXX") or die ("No connection could be made to the OpenRail Database"); mysql_select_db("autotrain"); //Set todays date from system and get HTTP parameters for the station,time to find trains and todays locations table. $date = date('Y-m-d'); $test = $_GET['station']; $time = $_GET['time']; $table = $_GET['table']; //Find the tiploc associated with the station being searched. $tiplocQuery = "SELECT tiploc_code FROM allstations WHERE c LIKE '$test';"; $tiplocResult =mysql_query($tiplocQuery); $tiplocRow = mysql_fetch_assoc($tiplocResult); $tiploc=$tiplocRow['tiploc_code']; //Now find the timetabled trains for the station where there exists no departure information. Goes back two hours to account for any late running. $timeTableQuery = "SELECT tiplocs.tps_description AS 'C', locations$table.public_departure, locations$table.id,schedules.stp_indicator ,schedules.train_uid FROM locations$table, tiplocs, schedules_cache, schedules,activations WHERE locations$table.id = schedules_cache.id AND schedules_cache.id = schedules.id AND schedules.id =activations.id AND '$date' BETWEEN schedules.date_from AND schedules.date_to AND locations$table.tiploc_code = '$tiploc' AND locations$table.real_departure LIKE '0' AND locations$table.public_departure NOT LIKE '0' AND locations$table.public_departure &gt;='$time'-300 AND locations$table.public_departure &lt;='$time'+300 AND schedules.runs_th LIKE '1' AND schedules_cache.destination = tiplocs.tiploc ORDER BY locations$table.public_departure ASC LIMIT 0,30;"; $timeTableResult=mysql_query($timeTableQuery); while($timeTablerow = mysql_fetch_assoc($timeTableResult)){ $output[] = $timeTablerow; } //Now for each id returned in the timetable, get the locations and departure times so the app may calculate expected arrival times. foreach ($output as $value) { $id = $value['id']; $realTimeQuery ="SELECT locations$table.id,locations$table.location_order,locations$table.arrival,locations$table.public_arrival, locations$table.real_arrival,locations$table.pass,locations$table.departure,locations$ table.public_departure,locations$table.real_departure,locations$table.location_cancelled, tiplocs.tps_description FROM locations$table,tiplocs WHERE id =$id AND locations$table.tiploc_code=tiplocs.tiploc;"; $realTimeResult =mysql_query($realTimeQuery); while($row3 = mysql_fetch_assoc($realTimeResult)){ $output3[] = $row3; } print json_encode($output3); print("*"); unset($output3); unset($id); } print('&gt;'); print json_encode($output); ?&gt; </code></pre> <p>Many Thanks Matt</p>
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    1. USMatthew Dutton
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    1. CO[**Please, don't use `mysql_*` functions in new code**](http://bit.ly/phpmsql). They are no longer maintained [and are officially deprecated](https://wiki.php.net/rfc/mysql_deprecation). See the [**red box**](http://j.mp/Te9zIL)? Learn about [*prepared statements*](http://j.mp/T9hLWi) instead, and use [PDO](http://php.net/pdo) or [MySQLi](http://php.net/mysqli) - [this article](http://j.mp/QEx8IB) will help you decide which. If you choose PDO, [here is a good tutorial](http://j.mp/PoWehJ).
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      1. POMore efficient way to do SQL queries
      1. USJohn Conde
    2. COOh right ok, thanks for the link. I'll change the way I do it. Still its the sql thats problem and causing the slow down any guidance there would be met with many thanks.
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      1. USMatthew Dutton
    3. CO@Matt: first work out how you're going to change your code-base (to use PDO or MySQLi), implement that change and then come back to us with specific question(s) to do with that code. This really isn't the place for speculative general advice or guidance.
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      1. USDavid Thomas
 

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