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  • Most efficient way to LIMIT results in a JOIN?

    - by johnnietheblack
    I have a fairly simple one-to-many type join in a MySQL query. In this case, I'd like to LIMIT my results by the left table. For example, let's say I have an accounts table and a comments table, and I'd like to pull 100 rows from accounts and all the associated comments rows for each. Thy only way I can think to do this is with a sub-select in in the FROM clause instead of simply selecting FROM accounts. Here is my current idea: SELECT a.*, c.* FROM (SELECT * FROM accounts LIMIT 100) a LEFT JOIN `comments` c on c.account_id = a.id ORDER BY a.id However, whenever I need to do a sub-select of some sort, my intermediate level SQL knowledge feels like it's doing something wrong. Is there a more efficient, or faster, way to do this, or is this pretty good? By the way... This might be the absolute simplest way to do this, which I'm okay with as an answer. I'm simply trying to figure out if there IS another way to do this that could potentially compete with the above statement in terms of speed.

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  • Sorting by some field and fetching whole tree from DB

    - by Niaxon
    Hello everyone, I am trying to do file browser in a tree form and have a problem to sort it somehow. I use PHP and MySQL for that. I've created mixed (nested set + adjacency) table 'element' with the following fields: element_id, left_key, right_key, level, parent_id, element_name, element_type (enum: 'folder','file'), element_size. Let's not discuss right now that it is better to move information about element (name, type, size) into other table. Function to scan specified directory and fill table work correctly. Noteworthy, i am adding elements to tree in specific order: folders first and only files. After that i can easily fetch and display whole table on the page using simple query: SELECT * FROM element WHERE 1=1 ORDER BY left_key With the result of that query and another function i can generate correct html code (<ul><li>... and so on). Now back to the question (finally, huh?). I am struggling to add sorting functionality. For example i want to order my result by size. Here i need to keep in my mind whole hierarchy of tree and rule: folders first, files later. I believe i can do that by generating in PHP recursive query: SELECT * FROM element WHERE parent_id = {$parentId} ORDER BY element_type (so folders would be first), size (or name for example) After that for each result which is folder i will send another query to get it's content. Also it's possible to fetch whole tree by left_key and after that sort it in PHP as array but i guess that would be worse :) I wonder if there is better and more efficient way to do such thing?

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  • Connecting a django application to a drupal database?

    - by Hans
    I have a 3 - 4000 nodes in a drupal 6 installation on mysql and want to access these data through my django application. I have used manage.py inspectdb to get a skeleton of a model structure. I guess that there are good/historical reasons for drupal's database schemes, but find that there are some hard to understand structure and that there are some challenges in applying django models on the database. Some experiences this far are: node and node revision are intertwined and I solved this by using a OneToOneField (don't need the versions). This meens that the node's body gets accessible through node.vid.body, but it works. Foreign keys need to define the proper db_column to sort out the primary keys. Terms need to use an intermediary table with ManyToManyField.through. Drupal stores both the original and the thumbnailed/resized versions of any image as files in the files table. Does anyone have experiences in accessing drupal data in django? Are there better solution to for example the node <- node revision relationship? Drupal stores time/dates as unix-style timestamps in integerfields. Any recommendations? How about time zones?

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  • Good Hosting Providers With Zend Framework Support

    - by manyxcxi
    I currently use ixwebhosting for my hosting services. They're cheap and work (most of the time). The databases are horribly slow, the servers are horribly slow, and their support (though usually prompt) is tough to deal with. That being said, they're cheap, I've got like 20 domains hosted in my account, none of them are high volume, and they work JUST good enough- until today. This isn't meant to be a condemnation of ixwh though. Their prices are very low for what they do offer and most things work just fine, most of the time. I need to be able to host web apps written with Zend Framework in a fairly easy fashion. The server performance can't be worse than what I've already had (a pretty low hurdle to clear), and I don't want to spend $30/mo. These are not money making websites- they're projects. My requirements are PHP 5.3, ZF support, MySQL databases, multiple domains- not much. Who should I look at, and who should I look out for? Also- I put this on SO instead of SF because of the Zend Framework specific requirement. If I'm wrong, do as you wish.

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  • Which of these methods provides for the fastest page loading?

    - by chromedude
    I am building a database in MySQL that will be accessed by PHP scripts. I have a table that is the activity stream. This includes everything that goes on on the website (following of many different things, liking, upvoting etc.). From this activity stream I am going to run an algorithm for each user depending on their activity and display relevant activity. Should I create another table that stores the activity for each user once the algorithm has been run on the activity or should I run the algorithm on the activity table every time the user accesses the site? UPDATE:(this is what is above except rephrased hopefully in an easier to understand way) I have a database table called activity. This table creates a new row every time an action is performed by a user on the website. Every time a user logs in I am going to run an algorithm on the new rows (since the users last login) in the table (activity) that apply to them. For example if the user is following a user who upvoted a post in the activity stream that post will be displayed when the user logs in. I want the ability for the user to be able to access previous content applying to them. Would it be easiest to create another table that saved the rows that have already been run over with the algorithm except attached to individual users names? (a row can apply to multiple different users)

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  • SQL return ORDER BY result as an array

    - by EarthMind
    Is it possible to return groups as an associative array? I'd like to know if a pure SQL solution is possible. Note that I release that I could be making things more complex unnecessarily but this is mainly to give me an idea of the power of SQL. My problem: I have a list of words in the database that should be sorted alphabetically and grouped into separate groups according to the first letter of the word. For example: ape broom coconut banana apple should be returned as array( 'a' => 'ape', 'apple', 'b' => 'banana', 'broom', 'c' => 'coconut' ) so I can easily created sorted lists by first letter (i.e. clicking "A" only shows words starting with a, "B" with b, etc. This should make it easier for me to load everything in one query and make the sorted list JavaScript based, i.e. without having to reload the page (or use AJAX). Side notes: I'm using PostgreSQL but a solution for MySQL would be fine too so I can try to port it to PostgreSQL. Scripting language is PHP.

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  • New user register, script auto create problems!

    - by SKY
    Hi, im currently trying to create a php script that when a new user register, a script (eg:wordpress,blog etc..) will install for them. I'm currently got the code below for just single setup, but how can i setup a form for multi user? which only allowing them to input the username (subdomain) and password. <?php class scriptname_Config { public static $title = 'new_script_title'; // Domain name and path where new script will installed in public static $domain = 'username.domain.com'; public static $absolutePath = '/new_register_username/'; // Settings for general mysql database public static $db = array( 'host' => 'localhost', 'database' => 'scriptname', 'user' => 'root', 'password' => '', 'prefix' => 'scriptname_' ); } define( 'scriptname_BASE_URL', 'http://'.scriptname_Config::$domain.scriptname_Config::$absolutePath ); ?> Or any tutorial that will help is appreciate! Thanks!

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  • How to load data on option box in php

    - by user225269
    I'm having trouble loading the mysql data on the html form option box using php. Here's my code: <?php $con = mysql_connect("localhost","myuname","mypassword"); if (!$con) { die('Could not connect: ' . mysql_error()); } mysql_select_db("school", $con); $idnum= mysql_real_escape_string($_POST['idnum']); $result = mysql_query("SELECT * FROM student WHERE IDNO='$idnum'"); ?> <?php while ( $row = mysql_fetch_array($result) ) { ?> <tr> <td width="30" height="35"><font size="2">*I D Number:</td> <td width="30"><input name="idnum" type="text" maxlength="5" value="<?php echo $row["IDNO"]; ?>" readonly="readonly"></td> </tr> My problem is loading it here: <td><font size="2">Gender</td> <td> <select name="gender" id="gender"> <font size="2"> <option value="<?php echo $line['IDNO']; ?> "><?php $line['GENDER'] ; ?></option> </select></td></td> The table looks like this: IDNO | GENDER 123 | M 321 | F What am I supposed to do?To load the exact gender corresponding to the IDNO?

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  • Calculating distance between two X,Y coordinates

    - by Umopepisdn
    I am writing a tool for a game that involves calculating the distance between two coordinates on a spherical plane 500 units across. That is, [0,0] through [499,499] are valid coordinates, and [0,0] and [499,499] are also right next to each other. Currently, in my application, I am comparing the distance between a city with an [X,Y] location respective to the user's own [X,Y] location, which they have configured in advance. To do this, I found this algorithm, which kind of works: Math.sqrt ( dx * dx + dy * dy ); Because sorting a paged list by distance is a useful thing to be able to do, I implemented this algorithm in a MySQL query and have made it available to my application using the following part of my SELECT statement: SQRT( POW( ( ".strval($sourceX)." - cityX ) , 2 ) + POW( ( ".strval($sourceY)." - cityY ) , 2 ) ) AS distance This works fine for many calculations, but does not take into account the fact that [0,0] and [499,499] are kitty-corner to one another. Is there any way I can tweak this algorithm to generate an accurate distance, given that 0 and 499 are adjacent? Thanks, -Umo

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  • How to get a category listing from Magento?

    - by alex
    I want to create a page in Magento that shows a visual representation of the categories.. example CATEGORY product 1 product 2 ANOTHER CATEGORY product 3 My problem is, their database is organised very differently to what I've seen in the past. They have tables dedicated to data types like varchar, int, etc. I assume this is for performance or similiar. I haven't found a way to use MySQL to query the database and get a list of categories. I'd then like to match these categories to products, to get a listing of products for each category. Unfortunately Magento seems to make this very difficult. Also I have not found a method that will work from within a page block.. I have created showcase.phtml and put it in the XML layout and it displays and runs it's PHP code. I was hoping for something easy like looping through $this-getAllCategories(); and then a nested loop inside with something like $category-getChildProducts(); Can anyone help me? Thank you!

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  • Most efficient way to make an activity log

    - by Nathan
    I am making a "recent activity" tab to profiles on my site and I also am going to have a log for moderators to see everything that happens on the site. This would require making an activity log of some sort. I just don't know what would be better. I have 2 options: Make a table called "activity" and then every time someone does something, add a record to it with the type of action, user id, timestamp, etc. Problem: table could get very long. Join all 3 tables (questions, answers, answer_comments) and then somehow show all these on the page in the order in which the action was taken. Problem: this would be extremely hard because I have no clue how I could make it say "John commented on an answer on Question Title Here" by just joining 3 tables. Does anyone know of a better way of making an activity log in this situation? I am using PHP and MySQL. If this is either too inefficient or hard I will probably just forget the Recent Activity tab on profiles but I still need an activity log for moderators. Here's some SQL that I started making for option 2, but this would not work because there is no way of detecting whether the action is a comment, question, or answer when I echo the info in a while loop: SELECT q.*, a.*, ac.* FROM questions q JOIN answers a ON a.questionid = q.qid JOIN answer_comments ac ON c.answerid = a.ans_id WHERE q.user = $userid AND a.userid = $userid AND ac.userid = $userid ORDER BY q.created DESC, a.created DESC, ac.created DESC Thanks in advance for any help!

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  • PHP and storing stats

    - by John
    Using PHP5 and the latest version of MySQL I want to be able to track impressions and clicks for business listings. My question is if I did this myself what would be the best method in storing it so I can run reports? Before I just had a table that had the listing id, user ip address and if it was a click or impression as well as the date it was tracked. However the database itself is approaching 2GB of data and its very slow, part of the problem is its a pretty simple script that includes impressions and clicks from anyone including search engines and basically anyone or anything that accesses the listing page. Is there an api or file out there that has an update to date list that can detect if the person viewing is a actually person and not a spider so I dont fill up the database with unneeded stats? Just looking for suggestions, do I just have a raw database that gets just the hits then a cron job at night tally up for the day for each listing for each ip and store the cumulative stats in a different table? Also what type of database should it be? Innodb? MyISAM?

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  • MySQLDB query not returning all rows

    - by RBK
    I am trying to do a simple fetch using MySQLDB in Python. I have 2 tables(Accounts & Products). I have to look up Accounts table, get acc_id from it & query the Products table using it. The Products tables has more than 10 rows. But when I run this code it randomly returns between 0 & 6 rows each time I run it. Here's the code snippet: # Set up connection con = mdb.connect('db.xxxxx.com', 'user', 'password', 'mydb') # Create cursor cur = con.cursor() # Execute query cur.execute("SELECT acc_id FROM Accounts WHERE ext_acc = '%s'" % account_num ) # account_num is alpha-numberic and is got from preceding part of the program # A tuple is returned, so get the 0th item from it acc_id = cur.fetchone()[0] print "account_id = ", acc_id # Close the cursor - I was not sure if I can reuse it cur.close() # Reopen the cursor cur = con.cursor() # Second query cur.execute("SELECT * FROM Products WHERE account_id = %d" % acc_id) keys = cur.fetchall() print cur.rowcount # This prints incorrect row count for key in keys: # Does not print all rows. Tried to directly print keys instead of iterating - same result :( print key # Closing the cursor & connection cur.close() con.close() The weird part is, I tried to step through the code using a debugger(PyDev on Eclipse) and it correctly gets all rows(both the value stored in the variable 'keys' as well as console output are correct). I am sure my DB has correct data since I ran the same SQL on MySQL console & got the correct result. Just to be sure I was not improperly closing the connection, I tried using with con instead of manually closing the connection and it's the same result. I did RTFM but I couldn't find much in it to help me with this issue. Where am I going wrong? Thank you. EDIT: I noticed another weird thing now. In the line cur.execute("SELECT * FROM Products WHERE account_id = %d" % acc_id), I hard-coded the acc_id value, i.e made it cur.execute("SELECT * FROM Products WHERE account_id = %d" % 322) and it returns all rows

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  • Password protect user image album

    - by Poland Rocks
    Hi Im making i photo sharint site I want to give the ability for my users to prevent the public to acces their albums with a password. Then they can give the password to the ones they want to be able to see it. To password protect their albums. Im thinking something like this, cant test it on this computer, should work ok. but as im a php/mysql beginner i wanna hear what you experts think if theres a better way/approach Albums id name owner password (if it isnt null the album is considered password protected) The code $id = isset($_GET['albumID']) ? intval($_GET['albumID']) : 0; $result = mysql_query("SELECT * FROM albums WHERE id = $id"); $row = mysql_fetch_object($result); // IS it password protected? if ($row->password != NULL) { echo "This album is password protected."; // User pressed "Enter" if (!empty($_POST['password'])) { $result = mysql_query("SELECT password FROM albums WHERE password = '".mysql_real_escape_string($_POST['password'])."'"); // Was It right password? if (mysql_num_rows($result) == 1) { $authed=1; } echo << <form method="post"> <input type="text" name="password" /> EOT; exit; } else $authed=1; if $authed==1 { // render albumimages etc }

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  • How to insert result of mysql_real_escape_string() into oracle database?

    - by Prat
    For inserting special characters in data like (,')etc., I am using musql_real_escape_string() function & it's working fine. Now I want to use same variable while inserting values in Oracle. $str = 'N.G.Palace\'s Building', 'xyzcity', '12345678','India','100001',12 Here $str is result of mysql_real_escape_string(). so it escapes special character. Now my code for oracle is like this-: $qry ="INSERT INTO Ora_table(ship_to_street, ship_to_city,ship_to_country, ship_to_telephone, order_id, record_no) VALUES(".$str); So my doubt is Oracle is not accepting values return by mysql_real_escape_string i.e. Palace\'s (like this as this mysql function attach \ before 'single quote)? So can anybody tell me ho9w can I use that variable $str to insert data into Oracle? Also I tried like this also-: "q"."'"."c".$str."c"."'" can we use this for multiple values like in my case...though still I am unable to inser data in oracle? plz help.

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  • PHP OOP class Sensative To Counter field name !

    - by Mac Taylor
    hey guys recently i managed to write a class for my stories , and everything is fine , unless counter field that stores page's hits here is my class : class nk_posts { var $data = array(); public function _data() { global $db; $result = $db->sql_query(" SELECT bt_stories.*, bt_tags.*, bt_topics.*, group_concat(DISTINCT bt_tags.tag ) as mytags, group_concat(DISTINCT bt_topics.topicname ) as mytopics FROM bt_stories,bt_tags,bt_topics WHERE CONCAT( ' ', bt_stories.tags, ' ' ) LIKE CONCAT( '%', bt_tags.tid, '%' ) AND CONCAT( ' ', bt_stories.associated, ' ' ) LIKE CONCAT( '%', bt_topics.topicid, '%' ) AND time<=now() AND section='news' AND approved='1' GROUP BY bt_stories.sid ORDER BY bt_stories.sid DESC "); while ($this->data = $db->sql_fetchrow($result)) { $this->sid = $this->data['sid']; $this->title = $this->data['title']; $this->counter = $this->data['counter']; //------Rest of Fields ------ $this->_output(); } } public function _output() { themeindex( $this->sid, $this->title, $this->counter, //------Rest of Fields ------ ); } } problem this class can't show counter filed value , but if i change counter field name to other thing like hit , .. everything goes fine im sure its okay if i write it in normal php mysql way , but i need this to be in OOP way any comment why it's sensitive to counter field name ?!

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  • PHP delete script, return to 'viewsubjects.php?classroom_id=NO VALUE'

    - by Derek
    Hi, As the title states... I am deleting a 'subject' from a 'classroom' I view classrooms, then can click on a classroom to view the subject for that classroom. So the link where I am viewing subjects looks like: viewsubjects.php?classroom=23 When the user selects the delete button (in a row) to remove a subject from a class, I simply want the user to be redirected back to the list of subjects for the classroom (exactly where they were before!!) So I though this is simply a case of calling up the classroom ID within my delete script. Here is what I have: EDIT: corrected spelling mistake in code (this was not the problem) $subject_id = $_GET['subject_id']; $classroom_id = $_GET['classroom_id']; $sql = "DELETE FROM subjects WHERE subject_id=".$subject_id; $result = mysql_query($sql, $connection) or die("MySQL Error: ".mysql_error()); header("Location: viewsubjects.php?classroom_id=".$classroom_id); exit(); The subject is being removed from the DB, but when I am redirected back the URI is displaying with an empty classroom ID like: viewsubjects.php?classroom_id= Is there a way to carry the classroom ID through successfully through the delete script so it can be displayed after, allowing the user to be redirected back to the page? Thanks for any help!

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  • ORDERBY "human" alphabetical order using SQL string manipulation

    - by supertrue
    I have a table of posts with titles that are in "human" alphabetical order but not in computer alphabetical order. These are in two flavors, numerical and alphabetical: Numerical: Figure 1.9, Figure 1.10, Figure 1.11... Alphabetical: Figure 1A ... Figure 1Z ... Figure 1AA If I orderby title, the result is that 1.10-1.19 come between 1.1 and 1.2, and 1AA-1AZ come between 1A and 1B. But this is not what I want; I want "human" alphabetical order, in which 1.10 comes after 1.9 and 1AA comes after 1Z. I am wondering if there's still a way in SQL to get the order that I want using string manipulation (or something else I haven't thought of). I am not an expert in SQL, so I don't know if this is possible, but if there were a way to do conditional replacement, then it seems I could impose the order I want by doing this: delete the period (which can be done with replace, right?) if the remaining figure number is more than three characters, add a 0 (zero) after the first character. This would seem to give me the outcome I want: 1.9 would become 109, which comes before 110; 1Z would become 10Z, which comes before 1AA. But can it be done in SQL? If so, what would the syntax be? Note that I don't want to modify the data itself—just to output the results of the query in the order described. This is in the context of a Wordpress installation, but I think the question is more suitably an SQL question because various things (such as pagination) depend on the ordering happening at the MySQL query stage, rather than in PHP.

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  • How can I integrate advanced computations into a database field?

    - by ciclistadan
    My biological research involves the measurement of a cellular structure as it changes length throughout the course of observation (capturing images every minute for several hours). As my data sets have become larger I am trying to store them in an Access database, from which I would like to perform various queries about their changes in size. I know that the SELECT statement can incorporate some mathematical permutations, but I have been unable to incorporate many of my necessary calculations (probably due to my lack of knowledge). For example, one calculation involves determining the rate of change during specifically defined periods of growth. This calculation is entirely dependent on the raw data saved in the table, therefore I didn't this it would be appropriate to just calculate it in excel prior to entry into the field. So my question is, what would be the most appropriate method of performing this calculation. Should I attempt to string together a huge SELECT calculation in my QUERY, or is there a way to use another language (I know perl?) which can be called to populate the new query field? I'm not looking for someone to write the code, just where is it appropriate to incorporate each step. Also, I am currently using Office Access but would be interested in any mySQL answers as I may be moving to this platform at a later date. Thanks all!

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  • How to reslove mysql_fetch_assoc(): problems!

    - by sky
    When i use the code below, im getting this error: Warning: mysql_fetch_assoc(): supplied argument is not a valid MySQL result resource when returning the data, anyone can fix it? Thanks! <?php $mysql_server_name="localhost"; $mysql_username=""; $mysql_password=""; $mysql_database=""; $conn=mysql_connect($mysql_server_name, $mysql_username, $mysql_password); ?> <?php $result = mysql_query("SELECT * FROM users"); $arrays = array(); while ($row = mysql_fetch_assoc($result)) { foreach ($row as $key => $val) { if (!array_contains_key($key)) { $arrays[$key] = array(); } $arrays[$key][] = $val; } } ?> <script type="text/javascript"> <?php foreach ($arrays as $key => $val) { print 'var ' . $key . ' = ' . json_encode($val) . ";\r\n"; } ?> </script>

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  • Applying iterative algorithm to a set of rows from database

    - by Corvin
    Hello, this question may seem too basic to some, but please bear with be, it's been a while since I dealt with decent database programming. I have an algorithm that I need to program in PHP/MySQL to work on a website. It performs some computations iteratively on an array of objects (it ranks the objects based on their properties). In each iteration the algorithm runs through all collection a couple of times, accessing various data from different places of the whole collection. The algorithm needs several hundred iterations to complete. The array comes from a database. The straightforward solution that I see is to take the results of a database query and create an object for each row of the query, put the objects to an array and pass the array to my algorithm. However, I'm concerned with efficacy of such solution when I have to work with an array of several thousand of items because what I do is essentially mirror the results of a query to memory. On the other hand, making database query a couple of times on each iteration of the algorithm also seems wrong. So, my question is - what is the correct architectural solution for a problem like this? Is it OK to mirror the query results to memory? If not, which is the best way to work with query results in such an algorithm? Thanks!

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  • Scalable way to store files on server (PHP)?

    - by Nathaniel Bennett
    I'm creating my first web application - a really simplistic online text editor. What I need to do is find the best way to store text based files - a lot of them. These text files can be past 10,000 words in size (text words not computer words.) in essence I want the text documents to be limitless in size. I was thinking about storing the text files in my MySQL database - but thought there was a better way. Instead I'm planing on storing the text files in XML based format in a directory on my server. The rows in the database define the name of the xml based text file and the user who created the text along with basic metadata. An ID is generated using a V4 GUID generator , which gives the text an id and stores the text in the "/store" directory on my server. The text definitions in my server contain this id, and the android app I'm developing gets the contents of the text file by retrieving the text definition and then downloading the text to the local device using the GUID in the text definition. I just think this is a botch job? how can I improve this system? There has been cases of GUID colliding. I don't want this to happen. A "slim" possibility isn't good enough - I need to make sure there is absolutely no chance in a GUID collision. I was planning on checking the database for texts that have the same id before storing the text with a particular id - I however believe with over 20,000 pieces of text in my database this would take an long time and produce unneeded stress on the server. How can I make GUID safe? What happens when a GUID collides? The server backend is going to be written in PHP.

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  • How to handle product ratings in a database

    - by Mel
    Hello, I would like to know what is the best approach to storing product ratings in a database. I have in mind the following two (simplified, and assuming a MySQL db) scenarios: Scenario 1: Create two columns in the product table to store number of votes and the sum of all votes. Use columns to get an average on the product display page: products(productedID, productName, voteCount, voteSum) Pros: I will only need to access one table, and thus execute one query to display product data and ratings. Cons: Write operations will be executed in a table whose original purpose is only to furnish product data. Scenario 2: Create an additional table to store ratings. products(productID, productName) ratings(productID, voteCount, voteSum) Pros: Isolate ratings into a separate table, leaving the products table to furnish data on available products. Cons: I will have to execute two separate queries on product page requests (one for data and another for ratings). In terms of performance, which of the following two approaches is best: Allow users to execute an occasional write query to a table that will handle hundreds of read requests? Execute two queries at every product page, but isolate the write query into a separate table. I'm a novice to database development, and often find myself struggling with simple questions such as these. Many thanks,

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  • Merging rows with uniqueness constraints

    - by Flambino
    I've got a little time-tracking web app (implemented in Rails 3.2.8 & MySQL). The app has several users who add their time to specific tasks, on a given date. The system is set up so a user can only have 1 time entry (i.e. row) per task per date. I.e. if you add time twice on the same task and date, it'll add time to the existing row, rather than create a new one. Now I'm looking to merge 2 tasks. In the simplest terms, merging task ID 2 into task ID 1 would take this time | user_id | task_id | date ------+----------+----------+----------- 10 | 1 | 1 | 2012-10-29 15 | 2 | 1 | 2012-10-29 10 | 1 | 2 | 2012-10-29 5 | 3 | 2 | 2012-10-29 and change it into this time | user_id | task_id | date ------+----------+----------+----------- 20 | 1 | 1 | 2012-10-29 <-- time values merged (summed) 15 | 2 | 1 | 2012-10-29 <-- no change 5 | 3 | 1 | 2012-10-29 <-- task_id changed (no merging necessary) I.e. merge by summing the time values, where the given user_id/date/task combo would conflict. I figure I can use a unique constraint to do a ON DUPLICATE KEY UPDATE ... if I do an insert for every task_id=2 entry. But that seems pretty inelegant. I've also tried to figure a way to first update all the rows in task 1 with the summed-up times, but I can't quite figure that one out. Any ideas?

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  • Joining tables, if percentage is above certain value

    - by CluelessGerman
    My question is similar to this one: Compare rows and get percentage However, little different. I adapted my question to the other post. I got 2 tables. First table: user_id | post_id 1 1 1 2 1 3 2 12 2 15 And second table: post_id | rating 1 1 1 2 1 3 2 1 2 5 3 null 3 1 3 4 12 4 15 1 So now I would like to count the rating for each post, in the second table. If the rating has more than, lets say, 50% positive ratings than I want to get the post_id and going it to the post_id from table one and add 1 to the user_id. At the end it would return the user_id with the number of positive posts. The result for above table would be: user_id | helpfulPosts 1 2 2 1 The post with post_id 1 and 3 have positive rating, because more than 50% have ratings of 1-3. The post with id = 2 is not positive, because the rating is exactly 50%. How would I achieve this? For clarification: It's a mysql rdbm and a positive post, is one where the number of rating_ids with 1, 2 and 3 are more than half of the overall rating. Basically the same thing, from the other thread I posted above.

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