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  • Average over a timeframe with missing data

    - by BHare
    Assuming a table such as: UID Name Datetime Users 4 Room 4 2012-08-03 14:00:00 3 2 Room 2 2012-08-03 14:00:00 3 3 Room 3 2012-08-03 14:00:00 1 1 Room 1 2012-08-03 14:00:00 2 3 Room 3 2012-08-03 14:15:00 1 2 Room 2 2012-08-03 14:15:00 4 1 Room 1 2012-08-03 14:15:00 3 1 Room 1 2012-08-03 14:30:00 6 1 Room 1 2012-08-03 14:45:00 3 2 Room 2 2012-08-03 14:45:00 7 3 Room 3 2012-08-03 14:45:00 8 4 Room 4 2012-08-03 14:45:00 4 I wanted to get the average user count of each room (1,2,3,4) from the time 2PM to 3PM. The problem is that sometimes the room may not "check in" at the 15 minute interval time, so the assumption has to be made that the previous last known user count is still valid. For example the check-in's for 2012-08-03 14:15:00 room 4 never checked in, so it must be assumed that room 4 had 3 users at 2012-08-03 14:15:00 because that is what it had at 2012-08-03 14:00:00 This follows on through so that the average user count I am looking for is as follows: Room 1: (2 + 3 + 6 + 3) / 4 = 3.5 Room 2: (3 + 4 + 4 + 7) / 4 = 4.5 Room 3: (1 + 1 + 1 + 8) / 4 = 2.75 Room 4: (3 + 3 + 3 + 4) / 4 = 3.25 where # is the assumed number based on the previous known check-in. I am wondering if it's possible to so this with SQL alone? if not I am curious of a ingenious PHP solution that isn't just bruteforce math, as such as my quick inaccurate pseudo code: foreach ($rooms_id_array as $room_id) { $SQL = "SELECT * FROM `table` WHERE (`UID` == $room_id && `Datetime` >= 2012-08-03 14:00:00 && `Datetime` <= 2012-08-03 15:00:00)"; $result = query($SQL); if ( count($result) < 4 ) { // go through each date and find what is missing, and then go to previous date and use that instead } else { foreach ($result) $sum += $result; $avg = $sum / 4; } }

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  • Best way to track impressions/clicks in a bespoke advertisement system?

    - by Martin Bean
    I've been asked to create a bespoke advertisement system despite suggesting open source alternatives such as OpenX and DoubleClick for Publishers (the former Google Ad Manager). I've got the basics of the system set up, i.e. uploading creatives, creating positions and a mechanism to place creatives within positions; however, the area I'm stuck with is impression and click tracking. At the moment an impression and click is stored with the creative, but this then means impressions/clicks can't be queried. For example, we can't find how many impressions were in position x between date y and date z. How would I go about storing that kind of data? My theory was store the creative ID, position ID and timestamp in a database table, but given the amount of traffic the site has this would produce a very large database very quickly. If any one could give me a pointer or two, that would be great.

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  • How much does an InnoDB table benefit from having fixed-length rows?

    - by Philip Eve
    I know that dependent on the database storage engine in use, a performance benefit can be found if all of the rows in the table can be guaranteed to be the same length (by avoiding nullable columns and not using any VARCHAR, TEXT or BLOB columns). I'm not clear on how far this applies to InnoDB, with its funny table arrangements. Let's give an example: I have the following table CREATE TABLE `PlayerGameRcd` ( `User` SMALLINT UNSIGNED NOT NULL, `Game` MEDIUMINT UNSIGNED NOT NULL, `GameResult` ENUM('Quit', 'Kicked by Vote', 'Kicked by Admin', 'Kicked by System', 'Finished 5th', 'Finished 4th', 'Finished 3rd', 'Finished 2nd', 'Finished 1st', 'Game Aborted', 'Playing', 'Hide' ) NOT NULL DEFAULT 'Playing', `Inherited` TINYINT NOT NULL, `GameCounts` TINYINT NOT NULL, `Colour` TINYINT UNSIGNED NOT NULL, `Score` SMALLINT UNSIGNED NOT NULL DEFAULT 0, `NumLongTurns` TINYINT UNSIGNED NOT NULL DEFAULT 0, `Notes` MEDIUMTEXT, `CurrentOccupant` TINYINT UNSIGNED NOT NULL DEFAULT 0, PRIMARY KEY (`Game`, `User`), UNIQUE KEY `PGR_multi_uk` (`Game`, `CurrentOccupant`, `Colour`), INDEX `Stats_ind_PGR` (`GameCounts`, `GameResult`, `Score`, `User`), INDEX `GameList_ind_PGR` (`User`, `CurrentOccupant`, `Game`, `Colour`), CONSTRAINT `Constr_PlayerGameRcd_User_fk` FOREIGN KEY `User_fk` (`User`) REFERENCES `User` (`UserID`) ON DELETE CASCADE ON UPDATE CASCADE, CONSTRAINT `Constr_PlayerGameRcd_Game_fk` FOREIGN KEY `Game_fk` (`Game`) REFERENCES `Game` (`GameID`) ON DELETE CASCADE ON UPDATE CASCADE ) ENGINE=INNODB CHARACTER SET utf8 COLLATE utf8_general_ci The only column that is nullable is Notes, which is MEDIUMTEXT. This table presently has 33097 rows (which I appreciate is small as yet). Of these rows, only 61 have values in Notes. How much of an improvement might I see from, say, adding a new table to store the Notes column in and performing LEFT JOINs when necessary?

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  • how can i make sure only a single record is inserted when multiple apache threads are trying to acce

    - by Ed Gl
    I have a web service (xmlrpc service to be exact) that handles among other things writing data into the database. Here's the scenario: I often receive requests to either update or insert a record. What I would do is this: If the record already exists, append to the record, If not, create a new record The issue is that there are certain times I would get a 'burst' of requests, which spawns several apache threads to handle the request. These 'bursts' would come within less than milliseconds of each other. I now have several threads performing #1 and #2. Often two threads would would 'pass' number #1 and actually create two duplicate records (except for the primary key). I'd like to use some locking mechanism to prevent other threads from accessing the table while the other thread finishes its work. I'm just afraid of using it because if something happens I don't want to leave the table locked. Is there a solid way of handling this? I'm open to using locks if I can do it properly. Thanks,

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  • How to get multiple counts with one SQL query?

    - by Crobzilla
    I am wondering how to write this query. I know this actual syntax is bogus, but it will help you understand what I am wanting. I need it in this format, because it is part of a much bigger query. SELECT distributor_id, COUNT(*) AS TOTAL, COUNT(*) WHERE level = 'exec', COUNT(*) WHERE level = 'personal' I need this all returned in one query. Also, it need to be in one row, so the following won't work: 'SELECT distributor_id, COUNT(*) GROUP BY distributor_id'

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  • join select from multiple row values?

    - by user1869132
    Two tables 1) product -------------------- id | Name | price 1 | p1 | 10 2 | p2 | 20 3 | p3 | 30 2) product_attributes: --------------------------------------------------- id | product_id | attribute_name | attribute_value --------------------------------------------------- 1 | 1 | size | 10 2 | 1 | colour | red 3 | 2 | size | 20 I need to join these two tables. In the where clause I need to match both the two rows attribute values. Is it possible to get the result based on two rows value. Here if size=10 and colour=red. Output should be 1 | p1 | 10 It could be greatly helpful to get a query for this.

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  • Where binary in SQL

    - by fire
    I have an SQL statement: SELECT * FROM customers WHERE BINARY login='xxx' AND password='yyyy' There are no blob/binary fields in the table, do I need the BINARY after the WHERE what else does it do?

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  • In SQL, why is "Distinct" not used in a subquery, when looking for some items "not showing up" in th

    - by Jian Lin
    Usually when looking for some items not showing up in the other table, we can use: select * from gifts where giftID not in (select giftID from sentgifts); or select * from gifts where giftID not in (select distinct giftID from sentgifts); the second line is with "distinct" added, so that the resulting table is smaller, and probably let the search for "not in" faster too. So, won't using "distinct" be desirable? Often than not, I don't see it being used in the subquery in such a case. Is there advantage or disadvantage of using it? thanks.

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  • 500 error on https, site loads fine [closed]

    - by jetlej
    Using http://web-sniffer.net/, I'm seeing a 500 internal error when accessing the https://www version of my site (https://moblized.com). However that URL loads perfectly fine with no errors. I was checking this because Google Webmaster is showing a bunch of 500 errors on my site. Also just noticed that I get a 200 success error if sniffing with HTTP 1.0, but a 500 with HTTP 1.1 Note: All other URL versions 301 redirect to https://www, eg. http://www , https:// , http:// FIXED: For any curious parties, there was one PHP bug that was causing a fatal error, but was still allowing the page to load. Turning on php_debug helped...

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  • Getting highest results in a JOIN

    - by Keithamus
    I've got three tables; Auctions, Auction Bids and Users. The table structure looks something like this: Auctions: id title -- ----- 1 Auction 1 2 Auction 2 Auction Bids: id user_id auction_id bid_amt -- ------- ---------- ------- 1 1 1 200.00 2 2 1 202.00 3 1 2 100.00 Users is just a standard table, with id and user name. My aim is to join these tables so I can get the highest values of these bids, as well as get the usernames related to those bids; so I have a result set like so: auction_id auction_title auctionbid_amt user_username ---------- ------------- -------------- ------------- 1 Auction 1 202.00 Bidder2 2 Auction 2 100.00 Bidder1 So far my query is as follows: SELECT a.id, a.title, ab.bid_points, u.display_name FROM auction a LEFT JOIN auctionbid ab ON a.id = ab.auction_id LEFT JOIN users u ON u.id = ab.user_id GROUP BY a.id This gets the single rows I am after, but it seems to display the lowest bid_amt, not the highest.

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  • How to refresh site if $_SESSION variable has changed

    - by 4ndro1d
    I'm writing in my $_SESSION variable from a database, when i clicked a link. public function getProjectById($id){ $query="SELECT * FROM projects WHERE id=\"$id\""; $result=mysql_query($query); $num=mysql_numrows($result); while ($row = mysql_fetch_object($result)) { $_SESSION['projectid'] = $row->id; $_SESSION['projecttitle'] = $row->title; $_SESSION['projectinfo'] = $row->info; $_SESSION['projecttext'] = $row->text; $_SESSION['projectcategory'] = $row->category; } } Now my variable is overwritten and I want to show these variables in my index.php like this: <div id="textContent"> <?php if(isset($_SESSION['projecttext']) && !empty($_SESSION['projecttext'])) { echo $_SESSION['projecttext']; }else { echo 'No text'; } ?></div> But of course, my page will not refresh automatically. How can I do that?

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  • Unique constraint with nullable column

    - by Álvaro G. Vicario
    I have a table that holds nested categories. I want to avoid duplicate names on same-level items (i.e., categories with same parent). I've come with this: CREATE TABLE `category` ( `category_id` int(10) unsigned NOT NULL AUTO_INCREMENT, `category_name` varchar(100) NOT NULL, `parent_id` int(10) unsigned DEFAULT NULL, PRIMARY KEY (`category_id`), UNIQUE KEY `category_name_UNIQUE` (`category_name`,`parent_id`), KEY `fk_category_category1` (`parent_id`,`category_id`), CONSTRAINT `fk_category_category1` FOREIGN KEY (`parent_id`) REFERENCES `category` (`category_id`) ON DELETE SET NULL ON UPDATE CASCADE ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_spanish_ci Unluckily, category_name_UNIQUE does not enforce my rule for root level categories (those where parent_id is NULL). Is there a reasonable workaround?

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  • Calculate distances and sort them

    - by Emir
    Hi guys, I wrote a function that can calculate the distance between two addresses using the Google Maps API. The addresses are obtained from the database. What I want to do is calculate the distance using the function I wrote and sort the places according to the distance. Just like "Locate Store Near You" feature in online stores. I'm going to specify what I want to do with an example: So, lets say we have 10 addresses in database. And we have a variable $currentlocation. And I have a function called calcdist(), so that I can calculate the distances between 10 addresses and $currentlocation, and sort them. Here is how I do it: $query = mysql_query("SELECT name, address FROM table"); while ($write = mysql_fetch_array($query)) { $distance = array(calcdist($currentlocation, $write["address"])); sort($distance); for ($i=0; $i<1; $i++) { echo "<tr><td><strong>".$distance[$i]." kms</strong></td><td>".$write['name']."</td></tr>"; } } But this doesn't work very well. It doesn't sort the numbers. Another challenge: How can I do this in an efficient way? Imagine there are infinite numbers of addresses; how can I sort these addresses and page them?

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  • Database normalization and duplicate values

    - by bretddog
    Consider a Parent / Child / GrandChild structure in a database table schema, or even a deeper hierarchy. These being in the same aggregate. One table DAYS keeps a single row per day, and has a "Date" field. This is the root table, or maybe a child of the root. No row can ever be deleted in this table. In this case, however complex my table schema looks like, however far away in the hierarchy any other table is, is there any reason why any other table would hold a Date value? Can't it instead just have a FK to the DAYS table. I obviously assume that the creation of these date fields happen not before such datefield exist in the DAYS table. I'm now thinking just about the date part to be relevant, not the time part. Not sure if all databases can store these individually. That's maybe relevant, but not really the focus of the question.

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  • Store database, good pattern for simultaneous access

    - by dygi
    I am kinda new to database designing so i ask for some advices or some kind of a good pattern. The situation is that, there is one database, few tables and many users. How should i design the database, or / and which types of queries should i use, to make it work, if users can interact with the database simultaneously? I mean, they have access to and can change the same set of data. I was thinking about transactions, but I am not sure, if that is the right / good / the only solution. I will appreciate some google keywords too.

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  • Symfony 1.4: Deleting a sfGuardUser

    - by Tom
    Hi, I'm having some trouble with the following... I have a sfGuardUser table set up normally, and it has a one-to-one relationship with a Profile table, which contains some additional user info. When a user wants to delete themselves from the site, I'd like to retain their info in the Profile table for various purposes BUT delete the sfGuardUser in order to keep that table cleaner/shorter (not just set it to inactive). I was under the impression that I could set the FK in the Profile table to NULL and then delete the sfGuardUser, but it seems the FK-constraint fails. Indeed, it seems I can't delete either and the queries fail: If I try to delete the sfGuardUser, the Profile table will have an invalid FK If I try to delete a Profile, the sfGuardUser will have an invalid FK Other than leaving outdated sfGuardUsers and Profiles in these tables, or having to use a cascaded delete to get rid of both, can anyone tell me if there's any other way around this? Thank you.

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  • Is there a fast way to change all the collation to utf8_unicode?

    - by Mark
    I have realised after making about 20 tables that I need to user utf8_unicode as opposed to utf8_general. What is the fastest way to change it using PHPMyAdmin? I had one idea: Export the database as SQL then using notepad run a find and replace on it and then reimport it... but it sounds like a bit of a headache. Is there a better way?

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  • How do I show the print with AJAX/jQuery?

    - by Doug
    So I'm trying to understand this whole AJAX/jQuery thing. Right now, when I run this PHP script alone, I would have to wait and watch the wheel spin until it's done with the loop and then it will load. while ( $row = mysql_fetch_array($res) ) { postcode_to_storm( $row['Test'] ); $dom = new DOMDocument(); @$dom->loadHTML($result); $xPath = new DOMXPath($dom); $failInvite = 'Rejected'; $findFalse = strpos($result, $failInvite); if ( $findFalse == true ) { $array[$i] = $row['Test']; $i++; echo $array[$i]}; } } Now, how do I use AJAX/jQuery to show echo $array[$i]}; everytime it is invoked instead of waiting for the whole process to complete?

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