Question

I’ve been coding a new dashboard, where I want to show various DB stats, mainly counting rows and setting the results into variables, its all working correctly, but I am a bit concerned that so many SELECT queries could become too heavy if a lot of users are entering or refreshing the page.

Appreciate your input 🙂

$tbl_players = players;

$xbox = mysql_query("SELECT * FROM $tbl_players WHERE Console = 'XBOX360'");
$ps3 = mysql_query("SELECT * FROM $tbl_players WHERE Console = 'PS3'");
$pc = mysql_query("SELECT * FROM $tbl_players WHERE Console = 'PC'");
$xbfa = mysql_query("SELECT * FROM $tbl_players WHERE Console = 'XBOX360' && fathread LIKE 'http%'");
$psfa = mysql_query("SELECT * FROM $tbl_players WHERE Console = 'PS3' && fathread LIKE 'http%'");
$pfa = mysql_query("SELECT * FROM $tbl_players WHERE Console = 'PC' && fathread LIKE 'http%'");
$xbcr = mysql_query("SELECT * FROM $tbl_players WHERE Console = 'XBOX360' && crthread LIKE 'http%'");
$pscr = mysql_query("SELECT * FROM $tbl_players WHERE Console = 'PS3' && crthread LIKE 'http%'");
$pcr = mysql_query("SELECT * FROM $tbl_players WHERE Console = 'PC' && crthread LIKE 'http%'");
while($row = mysql_fetch_array($xbox))
    {
$cxbox = mysql_num_rows($xbox);
}
while($row = mysql_fetch_array($ps3))
    {
$cps3 = mysql_num_rows($ps3);
}
while($row = mysql_fetch_array($pc))
    {
$cpc = mysql_num_rows($pc);
}
while($row = mysql_fetch_array($xbfa))
    {
$xboxfa = mysql_num_rows($xbfa);
}
while($row = mysql_fetch_array($psfa))
    {
$ps3fa = mysql_num_rows($psfa);
}
while($row = mysql_fetch_array($pfa))
    {
$pcfa = mysql_num_rows($pfa);
}
while($row = mysql_fetch_array($xbcr))
    {
$xboxcr = mysql_num_rows($xbcr);
}
while($row = mysql_fetch_array($pscr))
    {
$ps3cr = mysql_num_rows($pscr);
}
while($row = mysql_fetch_array($pcr))
    {
$pccr = mysql_num_rows($pcr);
}

$tbl_interactive = interactive;

$maximum = mysql_query("SELECT ID FROM $tbl_interactive ORDER BY ID DESC LIMIT 1");
while($max = mysql_fetch_array($maximum))
{
$cint = $max['ID'];
}
$xboxf = mysql_query("SELECT * FROM $tbl_interactive WHERE Console = 'XBOX360' && Type = 'Player' && $date < EndTime");
$xboxc = mysql_query("SELECT * FROM $tbl_interactive WHERE Console = 'XBOX360' && Type = 'Club' && $date < EndTime");
$ps3f = mysql_query("SELECT * FROM $tbl_interactive WHERE Console = 'PS3' && Type = 'Player' && $date < EndTime");
$ps3c = mysql_query("SELECT * FROM $tbl_interactive WHERE Console = 'PS3' && Type = 'Club' && $date < EndTime");
$pcf = mysql_query("SELECT * FROM $tbl_interactive WHERE Console = 'PC' && Type = 'Player' && $date < EndTime");
$pcc = mysql_query("SELECT * FROM $tbl_interactive WHERE Console = 'PC' && Type = 'Club' && $date < EndTime");
while($row = mysql_fetch_array($xboxf))
    {
$xboxfi = mysql_num_rows($xboxf);
}
while($row = mysql_fetch_array($xboxc))
    {
$xboxci = mysql_num_rows($xboxc);
}
while($row = mysql_fetch_array($ps3f))
    {
$ps3fi = mysql_num_rows($ps3f);
}
while($row = mysql_fetch_array($ps3c))
    {
$ps3ci = mysql_num_rows($ps3c);
}
while($row = mysql_fetch_array($pcf))
    {
$pcfi = mysql_num_rows($pcf);
}
while($row = mysql_fetch_array($pcc))
    {
$pcci = mysql_num_rows($pcc);
}

Many Thanks!

Answer 1

Yes, that is too many queries, way too much overhead, and too much heavy lifting to get the resultset you want.

You could get all nine of those counts from the $tbl_players table with a single statement, and on a single row. Those nine separate statements you have are preparing nine separate resultsets, and you’re fetching all those rows in the resultset to the client just to get a count. (Maybe there’s some optimization in there somewhere, but MySQL is preparing all those rows to return to the client.) It would be much more efficient to have MySQL just return the counts you want, using a statement something like this:

SELECT SUM(IF(p.Console = 'XBOX360' ,1,0))                             AS xbox
     , SUM(IF(p.Console = 'PS3'     ,1,0))                             AS ps3
     , SUM(IF(p.Console = 'PC'      ,1,0))                             AS pc
     , SUM(IF(p.Console = 'XBOX360' AND p.fathread LIKE 'http%' ,1,0)) AS xbfa
     , SUM(IF(p.Console = 'PS3'     AND p.fathread LIKE 'http%' ,1,0)) AS psfa
     , SUM(IF(p.Console = 'PC'      AND p.fathread LIKE 'http%' ,1,0)) AS pfa
     , SUM(IF(p.Console = 'XBOX360' AND p.crthread LIKE 'http%' ,1,0)) AS xbfr
     , SUM(IF(p.Console = 'PS3'     AND p.crthread LIKE 'http%' ,1,0)) AS pscr
     , SUM(IF(p.Console = 'PC'      AND p.crthread LIKE 'http%' ,1,0)) AS pcr
  FROM $tbl_players p

That gets you back a single row, with nine values. That would cut down on the amount of code you’ve got considerably, and significantly improve performance.

Similarly, you can get all those counts from the $tbl_interactive table with a single statement as well:

SELECT SUM(IF(t.Console = 'XBOX360' AND t.Type = 'Player' ,1,0)) AS xbfi
     , SUM(IF(t.Console = 'XBOX360' AND t.Type = 'Club'   ,1,0)) AS xbci
     , SUM(IF(t.Console = 'PS3'     AND t.Type = 'Player' ,1,0)) AS psfi
     , SUM(IF(t.Console = 'PS3'     AND t.Type = 'Club'   ,1,0)) AS psci
     , SUM(IF(t.Console = 'PC'      AND t.Type = 'Player' ,1,0)) AS pcfi
     , SUM(IF(t.Console = 'PC'      AND t.Type = 'Club'   ,1,0)) AS pcci
  FROM $tbl_interactive t
 WHERE t.Console IN ('XBOX360','PS3','PC')
   AND t.Type IN ('Player','Club')
   AND $date < t.EndTime

---

while($row = mysql_fetch_array($tbl_interactive_counts))
{
    $xboxfi = $row["xbfi"];
    $xboxci = $row["xbci"];
    $ps3fi  = $row["psfi"];
    $ps3ci  = $row["psci"];
    $pcfi   = $row["pcfi"];
    $pcci   = $row["pcci"];
}

---

FOLLOWUP:

It’s possible that the SQL statements above to return a NULL rather than a zero, when there are no rows that satisfy the predicates (that is, match the WHERE clause). To have the statement return a count of zero in place of the NULL, we can use the MySQL IFNULL() function as convenient shorthand:

SELECT IFNULL(SUM(IF(t.Console = 'XBOX360' AND t.Type = 'Player' ,1,0)),0) AS xbfi
     , IFNULL(SUM(IF(t.Console = 'XBOX360' AND t.Type = 'Club'   ,1,0)),0) AS xbci
     , IFNULL(SUM(IF(t.Console = 'PS3'     AND t.Type = 'Player' ,1,0)),0) AS psfi
     , IFNULL(SUM(IF(t.Console = 'PS3'     AND t.Type = 'Club'   ,1,0)),0) AS psci
     , IFNULL(SUM(IF(t.Console = 'PC'      AND t.Type = 'Player' ,1,0)),0) AS pcfi
     , IFNULL(SUM(IF(t.Console = 'PC'      AND t.Type = 'Club'   ,1,0)),0) AS pcci
  FROM $tbl_interactive t
 WHERE t.Console IN ('XBOX360','PS3','PC')
   AND t.Type IN ('Player','Club')
   AND $date < t.EndTime

Note that we’ve just wrapped an expression: IFNULL(expr,0)

That’s just a shorthand equivalent to: IF(expr IS NULL, 0, expr)

also equivalent to the ANSI standard: CASE WHEN expr IS NULL THEN 0 ELSE expr END

(Using IFNULL, we only have to specify expr one time.)

---

Or, you could let MySQL return the NULL, and handle the replacment of the NULL with a zero in PHP. (Note that fetched value in the $row array will still contain the NULL, but a zero will be assigned to the scalar:

$xboxfi = is_null($row["xbfi"]) ? 0 : $row["xbfi"] ;