My Current query is:
SELECT DISTINCT DATE(vote_timestamp) AS Date, COUNT(*) AS TotalVotes FROM `votes`
WHERE vote_target_id='83031'
GROUP BY DATE(vote_timestamp) ORDER BY DATE(vote_timestamp) DESC LIMIT 30
(line breaks separated for readability)
Where vote_timestamp is a time for each "vote", Count(*) is the count for that day, and vote_target_id is the specific target of the vote.
Currently, this works for all days in which the target has at least one "vote", but I would like it to also return TotalVotes as 0 for days where there are no votes, rather than having no row at all.
Can this (and how?) be done in MySQL or PHP? (either is fine, as it is futher processed by PHP so either code can be used).
Thank you
The problem is how to generate records for days that have no rows. This SO question has some approaches.
Looking at that solution, it looks like for me it's much simpler to do this quick fix that sorta works.
$result = mysql_query($sql) or die('Internal Database Error');
if (mysql_num_rows($result) == 0) { return false; }
while($row = mysql_fetch_assoc( $result )) {
$votes[$row['Date']] = $row['TotalVotes'];
}
// fill 0s with php rather than using mysql
$dates = array_keys($votes);
for ($t = strtotime($dates[count($dates)-1]); $t <= time(); $t +=86400) {
$date = date('Y',$t).'-'.date('m',$t).'-'.date('d',$t);
if (!array_key_exists($date,$votes)) {
$votes[$date] = 0;
}
}
thanks though,
Related
I need help optimizing the below querys for a recurrent calendar i've built.
if user fail to accomplish all task where date
This is the query i use inside a forech which fetched all dates that the current activity is active.
This is my current setup, which works, but is very slow.
Other string explained:
$today=date("Y-m-d");
$parts = explode($sepparator, $datespan);
$dayForDate2 = date("l", mktime(0, 0, 0, $parts[1], $parts[2], $parts[0]));
$week2 = strtotime($datespan);
$week2 = date("W", $week2);
if($week2&1) { $weektype2 = "3"; } # Odd week 1, 3, 5 ...
else { $weektype2 = "2"; } # Even week 2, 4, 6 ...
Query1:
$query1 = "SELECT date_from, date_to, bok_id, kommentar
FROM bokningar
WHERE bokningar.typ='2'
and date_from<'".$today."'";
function that makes the foreach move ahead one day at the time...
function date_range($first, $last, $step = '+1 day', $output_format = 'Y-m-d' )
{
$dates = array();
$current = strtotime($first);
$last = strtotime($last);
while( $current <= $last ) {
$dates[] = date($output_format, $current);
$current = strtotime($step, $current);
}
return $dates;
}
foreach:
foreach (date_range($row['date_from'], $row['date_to'], "+1 day", "Y-m-d")
as $datespan)
if ($datespan < $today)
Query 2:
$query2 = "
SELECT bok_id, kommentar
FROM bokningar b
WHERE b.typ='2'
AND b.bok_id='".$row['bok_id']."'
AND b.weektype = '1'
AND b.".$dayForDate2." = '1'
AND NOT EXISTS
(SELECT t.tilldelad, t.bok_id
FROM tilldelade t
WHERE t.tilldelad = '".$datespan."'
AND t.bok_id='".$row['bok_id']."')
OR b.typ='2'
AND b.bok_id='".$row['bok_id']."'
AND b.weektype = '".$weektype2."'
AND b.".$dayForDate2." = '1'
AND NOT EXISTS
(SELECT t.tilldelad, t.bok_id
FROM tilldelade t
WHERE t.tilldelad = '".$datespan."'
AND t.bok_id='".$row['bok_id']."')";
b.weektype is either 1,2 or 3 (every week, every even week, every uneven week)
bokningar needs INDEX(typ, date_from)
Instead of computing $today, you can do
and date_from < CURDATE()
Are you running $query2 for each date? How many days is that? You may be able to build a table of dates, then JOIN it to bokningar to do all the SELECTs in a single SELECT.
When doing x AND y OR x AND z, first add parenthes to make it clear which comes first AND or OR: (x AND y) OR (x AND z). Then use a simple rule in Boolean arithmetic to transform it into a more efficient expression: x AND (y OR z) (where the parens are necessary).
The usual pattern for EXISTS is EXISTS ( SELECT 1 FROM ... ); there is no need to list columns.
If I am reading it correctly, the only difference is in testing b.weektype. So the WHERE can be simply
WHERE b.weektype IN ('".$weektype2."', '1')
AND ...
There is no need for OR, since it is effectively in IN().
tilldelade needs INDEX(tilldelad, bok_id), in either order. This should make the EXISTS(...) run faster.
Finally, bokningar needs INDEX(typ, bok_id, weektype) in any order.
That is a lot to change and test. See if you can get those things done. If it still does not run fast enough, start a new Question with the new code. Please include SHOW CREATE TABLE for both tables.
I want select X records from database (in PHP script), then sleep 60 seconds after continue the next 60 results...
SO:
SELECT * FROM TABLE WHERE A = 'B' LIMIT 60
SELECT SLEEP(60);
....
SELECT * FROM TABLE WHERE A = 'B' LIMIT X **where X is the next 60 results, then**
SELECT SLEEP(60);
AND etc...
How can I achievement this?
There is no such thing as "the next 60 records". SQL tables represent unordered sets. Without an order by, a SQL statement can return a result set in any order -- and even in different orders on different executions.
Hence, you first need something to guarantee the ordering . . . that is, an order by with keys that uniquely identify each row.
You can then use offset/limit to accomplish what you want. Or, you could put the code into a stored procedure and use a while loop. Or, you could do this on the application side.
In PHP:
<?php
// obtain the database connection, there's a heap of examples on the net, assuming you're using a library like mysqlite
$offset = 0;
while (true) {
if ($offset == 0) {
$res = $db->query('SELECT * FROM TABLE WHERE A = 'B' LIMIT 60');
} else {
$res = $db->query('SELECT * FROM TABLE WHERE A = 'B' LIMIT ' . $offset . ',60');
}
$rows = $db->fetch_assoc($res);
sleep(60);
if ($offset >= $some_arbitrary_number) {
break;
}
$offset += 60;
}
What you're doing is gradually incrementing the limit field by 60 until you reach a limit. The easiest way to do it is in a control while loop using true for the condition and break when you reach your invalid condition.
I have 2 mysql tables with 500.000 items
first with items price, items id, and ticket number
second with ticket_number, date of sales and total_price of ticket
by now i use this query
SELECT items.pri,ticket.date,items.crd,items.plu
FROM items ,ticket
WHERE
(items.crd = 25 OR items.crd = 30) AND items.SeqNbr = ticket.SeqNbr
then in php:
$val_1 = array();
$price1 = 0;
while($row = mysql_fetch_array($query))
{
if($row['crd'] == 25)
{
$prix = $row['pri'];
if($prix != $price1)
{
$val_1[] = array( (int)$row['date']*1000,(float)$row['pri']);
$price1 = $prix;
}
}
}
return:
[[1388552879000,1.519],[1389136505000,1.498],[1392420222000,1.514],[1394667334000,1.499],[1395373887000,1.478],[1395963467000,1.499],[1396649284000,1.52],[1397513210000,1.542],[1398384245000,1.556],[1399347974000,1.536],[1400910286000,1.553],[1403216692000,1.58],[1405029076000,1.563]]
goal is obtain an array with price change and date to build a charts of price fluctuation.
but with more than 500.000 records this is extremly slow (15 sec)
is there any possibilities to build mysql query that return the same array ?
Thanks
First you need to check where is the bottleneck, on the query or on the loop.
If it is on the query, check if you have the right index. If not, try adding index for the fields items.crd, items.SeqNbr and ticket.SeqNbr.
I'm just a beginner at mysql so in school we got task to do. It goes like this. Display / print 10% of all books from books in falling order. So i tried to use limit, but it doesn't work. What can i do? My code i've tried to use:
select title, price from book
order by price desc
limit (select count(*)*0.1 from book);
thank you for your answers!
limit values have to be hard-coded constants. You can't use variables on them, e.g. select ... limit #somevar is a syntax error. You also can't use sub-queries or other dynamic values either. So you're stuck with either fetching the row count ahead of time and stuff it into the query string as a "hard-coded" value:
$ten_percent = get_from_database('select count(*) / 10 from book');
$sql = "SELECT .... LIMIT $ten_percent";
Or you simply fetch everything and then abort your loop once you've reached 10%:
$sql = "SELECT ....";
$result = mysql_query($sql) or die(mysql_error());
$total_rows = mysql_num_rows($result);
$fetched = 0;
while($row = mysql_fetch_assoc()) {
$fetched++;
if ($fetched >= ($total_rows / 10)) {
break; // abort the loop at 10%
}
... do stuff with $row
}
I'd like to count the number events that occur on each day over the last month, but also include a count of zero when no events are found. Is that possible?
Here's what I'm starting from...
SELECT COUNT(*) AS count,
DATE(usage_time_local) AS d
FROM usages
WHERE user_id=136
AND DATE(usage_time_local) >= DATE('2011-04-24')
AND DATE(usage_time_local) <= DATE('2011-05-24')
GROUP BY DATE(usage_time_local);
UPDATE: Given the answer, I implemented a code solution by initializing a loop and then filling in the details.
$dailyCount = array();
for( $i=1; $i<=30; $i++ ) {
$day = date('Y-m-d',(time()-($i*24*60*60)));
$dailyCount[$day] = 0;
}
foreach( $statement as $row ) {
$dailyCount[$row['d']] = $row['count'];
}
You can't do this with standard SQL queries - you'd be trying to group on a date(s) that doesn't exist in the table.
Standard workaround is to make a temporary table that contains the date range in sequential order with no gaps, join that against your table and do the count/aggregate as usual.