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  • Collaborative filtering in MySQL ?

    - by user281434
    Hi I'm trying to develop a site that recommends items(fx. books) to users based on their preferences. So far, I've read O'Reilly's "Collective Intelligence" and numerous other online articles. They all, however, seem to deal with single instances of recommendation, for example if you like book A then you might like book B. What I'm trying to do is to create a set of 'preference-nodes' for each user on my site. Let's say a user likes book A,B and C. Then, when they add book D, I don't want the system to recommend other books based solely other users experience with book D. I wan't the system to look up similar 'preference-nodes' and recommend books based on that. Here's an example of 4 nodes: User1: 'book A'->'book B'->'book C' User2: 'book A'->'book B'->'book C'->'book D' user3: 'book X'->'book Y'->'book C'->'book Z' user4: 'book W'->'book Q'->'book C'->'book Z' So a recommendation system, as described in the material I've read, would recommend book Z to User 1, because there are two people who recommends Z in conjuction with liking C (ie. Z weighs more than D), even though a user with a similar 'preference-node', User2, would be more qualified to recommend book D because he has a more similar interest-pattern. So does any of you have any experience with this sort of thing? Is there some things I should try to read or does there exist any open source systems for this? Thanks for your time! Small edit: I think last.fm's algorithm is doing exactly what I my system to do. Using the preference-trees of people to recommmend music more personally to people. Instead of just saying "you might like B because you liked A"

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  • Fetch data from multiple MySQL tables

    - by Jon McIntosh
    My two tables look like this: TABLE1 TABLE2 +--------------------+ +--------------------+ |field1|field2|field3| and |field2|field4|field5| +--------------------+ +--------------------+ I am already running a SELECT query for TABLE1, and assorting all of the data into variables: $query = "SELECT * FROM TABLE1 WHERE field2 = 2"; $result = mysql_query($query); $num_rows = mysql_num_rows($result); if((!is_bool($result) || $result) && $num_rows) { while($row = mysql_fetch_array($result)) { $field1 = $row['field1']; $field2 = $row['field2']; $field3 = $row['field3']; } } What I want to do is get the data from 'field4' on TABLE2 and add it to my variables. I would want to get field4 WHERE field2 = 2

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  • PHP, MySQL: Receive email, auto search in DB & send email based on the results

    - by Devner
    Hi all, Visitors can contact staff by means of contact form (visitor needs to submit email as well). This will be stored in DB. Now considering that staff responds to this message, the reply from the staff would be sent to the visitors email directly. Say if the user wants to follow up on the message sent by the staff, I would like the visitor to just hit the reply button in his email service & send me his questions on the same topic, but just retain the ID in the Subject line. So when the visitor send this email, I would like to receive the email & at the same time, try to search in my DB if the ID that is present in the email subject, actually exists in the system. If yes, that would be sent back to the same staff member who handled the response previously or it would be assigned to a new staff member. That being said, I was thinking of how to do this. The part where I am really held up is when the staff receives the actual email from the visitors email, how can I check the DB? Say I am/staff is receiving emails at [email protected]. When visitor sends reply email, then it would be sent to [email protected]. How can I check to see if the ID in the subject line of the email that I received at [email protected], actually exists in my DB in my website? This is where I am really stuck. Looking forward for your replies. Thank you.

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  • mysql: how to set max_allowed_packet for shared hosting?

    - by Sadi
    Hello, I need to set (increase) max_allowed_packet. But the problem is I am using a shared hosting. So, I can not access the .ini or .cnf file. Also I can not use the SET command. How can I am able to set a value (actually increase) for the max_allowed_packet, without asking the hosting support. I have no SSH access there. EDIT: I am trying to use VB 4.0.3. In there the attachment size is limited by it. So, I do not think splitting the file can be an option in this case. Thank you Sadi

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  • how to atomically claim a row or resource using UPDATE in mysql

    - by Igor
    i have a table of resources (lets say cars) which i want to claim atomically. if there's a limit of one resource per one user, i can do the following trick: UPDATE cars SET user = 'bob' WHERE user IS NULL LIMIT 1 SELECT * FROM cars WHERE user IS bob that way, i claim the resource atomically and then i can see which row i just claimed. this doesn't work when 'bob' can claim multiple cars. i realize i can get a list of cars already claimed by bob, claim another one, and then SELECT again to see what's changed, but that feels hackish. What I'm wondering is, is there some way to see which rows i just updated with my last UPDATE? failing that, is there some other trick to atomically claiming a row? i really want to avoid using SERIALIZABLE isolation level. If I do something like this: 1 SELECT id FROM cars WHERE user IS NULL 2 <here, my PHP or whatever picks a car id> 3 UPDATE cars SET user = 'bob' WHERE id = <the one i picked> would REPEATABLE READ be sufficient here? in other words, could i be guaranteed that some other transactions won't claim the row my software has picked during step 2?

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  • fast retrieval from MYSQL DB

    - by trojanwarrior3000
    I have a table of users - It contains around millions of rows (user-id is the primary key). I just want to retrieve user-id and their joining date. using "select user-id,joining date from table user" requires lot of time.Is there a fast way to query/retrieve the same data from this table?

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  • MySQL GROUP BY and JOIN

    - by christian
    Guys what's wrong with this SQL query: $sql = "SELECT res.Age, res.Gender, answer.*, $get_sum, SUM(CASE WHEN res.Gender='Male' THEN 1 else 0 END) AS males, SUM(CASE WHEN res.Gender='Female' THEN 1 else 0 END) AS females FROM Respondents AS res INNER JOIN Answers as answer ON answer.RespondentID=res.RespondentID INNER JOIN Questions as question ON answer.Answer=question.id WHERE answer.Question='Q1' GROUP BY res.Age ORDER BY res.Age ASC"; the $get_sum is an array of sql statement derived from another table: $sum[]= "SUM(CASE WHEN answer.Answer=".$db->f("id")." THEN 1 else 0 END) AS item".$db->f("id"); $get_sum = implode(', ', $sum); the query above return these values: Age: 20 item1 0 item2 1 item3 1 item4 1 item5 0 item6 0 Subtotal for Age 20 3 Age: 24 item1 2 item2 2 item3 2 item4 2 item5 1 item6 0 Subtotal for Age 24 9 It should return: Subtotal for Age 20 1 Subtotal for Age 24 2 In my sample data there are 3 respondents 2 are 24 yrs of age and the other one is 20 years old.

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  • Mysql data convert

    - by Sergio
    Is it possible to do DATE_SUB( ".$date." , INTERVAL 100 DAY ) if the type of the column where the date is stored is varchar(255) or I need to convert that column to "DATE" type?

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  • MySQL DATETIME format comparison - is strtotime needed?

    - by Steffan
    I've been doing something along the lines of.. $dt1 = '1000-01-01 00:00:00'; //really some val from db $dt2 = '1000-01-01 00:00:10'; //another val maybe db maybe formatted if(strtotime($dt1) > strtotime($dt2){ //do something } Is the strtotime needed? can i do a more direct comparison on the datetime formatted strings? i.e. if($dt1 > $dt2){ //do something } Will that always work?

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  • Script working with mysql and php into a textarea and back

    - by Tribalcomm
    I am trying to write a custom script that will keep a list of strings in a textarea. Each line of the textarea will be a row from a table. The problem I have is how to work the script to allow for adding, updating, or deleting rows based on a submit. So, for instance, I currently have 3 rows in the database: john sue mark I want to be able to delete sue and add richard and it will delete the row with sue and insert a row for richard. My code so far is as follows: To query the db and list it in the textarea: $basearray = mysql_query("SELECT name FROM mytable ORDER BY name"); <textarea name="names" cols=6 rows=12>'); <?php foreach($basearray as $base){ echo $base->name."\n"; } ?> </textarea> After the submit, I have: <?php $namelist = $_REQUEST[names]; $newarray = explode("\n", $namelist); foreach($newarray as $name) { if (!in_array($name, $basearray)) { mysql_query(DELETE FROM mytable WHERE word='$name'"); } elseif (in_array($name, $basearray)) { ; } else { mysql_query("INSERT INTO mytable (name) VALUES ("$name")"); } } ?> Please tell me what I am doing wrong. I am not getting any functions to work when I edit the contents of the textarea. Thanks!

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  • MySQL & PHP - Creating Multiple Parent Child Relations

    - by Ashok
    Hi, I'm trying to build a navigation system using categories table with hierarchies. Normally, the table would be defined as follows: id (int) - Primary key name (varchar) - Name of the Category parentid (int) - Parent ID of this Category referenced to same table (Self Join) But the catch is that I require that a category can be child to multiple parent categories.. Just like a Has and Belongs to Many (HABTM) relation. I know that if there are two tables, categories & items, we use a join table categories_items to list the HABTM relations. But here i'm not having two tables but only table but should somehow show HABTM relations to itself. Is this be possible using a single table? If yes, How? If not possible, what rules (table naming, fields) should I follow while creating the additional join table? I'm trying to achieve this using CakePHP, If someone can provide CakePHP solution for this problem, that would be awesome. Even if that's not possible, any solution about creating join table is appreciated. Thanks for your time.

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  • MySQL query cache and PHP variables

    - by Saif Bechan
    I have seen the following statement made about the query cache: // query cache does NOT work $r = mysql_query("SELECT username FROM user WHERE signup_date >= CURDATE()"); // query cache works! $today = date("Y-m-d"); $r = mysql_query("SELECT username FROM user WHERE signup_date >= '$today'"); So the query cache only works on the second query. I was wondering if the query cache will also work on this: define('__TODAY',date("Y-m-d")); $r = mysql_query("SELECT username FROM user WHERE signup_date >= '".__TODAY."'");

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  • mysql complex key or + auto increment key (guid)

    - by darko
    Hi, I have not very big db. I am using auto increment primary keys and in my case there is no problem with that. GUID is not necessary. I have a table containing this fields: from_destination to_testination shipper quantity Where the fields 1,2,3 needs to be unique. Also I have second table that for the fields 1,2,3 stores bought quantities per day One to many. from_destination to_destination shipper date reserved_quantity case 1 Is it better to make fields 1,2,3 as primary complex key in the first table and the same fields in the second table to be foreign key First table from_destination | to_destination | primary shipper | quaitity Second table second_id - autoincrement primary from_destination | to_destination | foreign key shipper | date reserved_quantity Case 2 or just to add auto increment filed in the first table and make fields 1,2,3 unique. In the second table there will be one ingeger foreign key pointing to the first table, and one auto increment key for the table. First table first_id - autoincrement primary from_destination | to_destination | unique shipper | quaitity Second table second_id - autoincrement primary first_id - forein date reserved_quantity If so why we need complex keys, when we can have one field auto increment or GUID and all other fields that are candidates for complex key to be unique. Regards

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  • Setting up MySQL database

    - by mathew
    I do have single database and near about 11 tables. while my web page is opening informations from these 11 tables will be accessed same time. according to my current settings what I did now is for each table database is opening and closing. say I had given username and password to open databse for each table and close after retrieving information from that table. Is this the right way to do it?? I feel because of this the database is opeing and closing 11 times!!!! Am I right?? is this the right way to do that?? Oh well I do have some tables which update date is differ from others... THanks Mathew

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  • Special characters in PHP / MySQL

    - by Jonathan
    Hi, I have in the database words that include special character (in Spanish mostly, like tildes). In the database everything is saved and shown correctly with PHPmyAdmin, but when I get the data (using PHP) and display it in a browser, I get a weird character, like a "?" with a square... I need a general fix so I don't need to escape each character every time, and also I would be able to insert special Spanish characters from a PHP form into the database... The HTML is correct: <meta http-equiv="content-type" content="text/html; charset=utf-8" /> All tables and databas are set to utf8_spanish The character I get: ? Any suggestions??? Thanks!!!

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  • Select from mysql by day with different timezones (php)

    - by Adam
    I'm storing leads in a database, and each lead has a datetime field with a PST timezone based date & time. I want my user to be able to display all leads from a certain date (e.g. today, yseterday), and choose the timezone. E.g. if I want to see all leads that were generated yesterday in EST timezone, I need to first convert (or read) all the datetime values to EST, and then only select those who are in the right range (yesterday). What would be the best way to do that?

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  • MySQL optimized sentence

    - by Ivan
    I have a simple table where I have to extract some records. The problem is that the evaluation function is a very time-consuming stored procedure so I shouldn't to call it twice like in this sentence: SELECT *, slow_sp(row) FROM table WHERE slow_sp(row)>0 ORDER BY dist DESC LIMIT 10 First I thought in optimize like this: SELECT *, slow_sp(row) AS value FROM table WHERE value>0 ORDER BY dist DESC LIMIT 10 But it doesn't works due "value" is not processed when the WHERE clause is evaluated. Any idea to optimize this sentence? Thanks.

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  • MySQL top count({column}) with a limit

    - by Josh K
    I have a table with an ip address column. I would like to find the top five addresses which are listed. Right now I'm planning it out the following: Select all distinct ip addresses Loop through them all saying count(id) where IP='{ip}' and storing the count List the top five counts. Downsides include what if I have 500 ip addresses. That's 500 queries I have to run to figure out what are the top five. I'd like to build a query like so select ip from table where 1 order by count({distinct ip}) asc limit 5

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  • MySQL - How do I inner join sorting the joined data

    - by Gary
    I'm trying to write a report which will join a person, their work, and their hourly wage at the time of work. I cannot seem to figure out the best way to join the person's cost when the date is less than the date of the work. Let's say a person cost $30 per hour at the start of the year then got a $10 raise o Feb 5 and another on Mar 1. 01/01/2010 $30.00 (per hour) 02/05/2010 $40.00 03/01/2010 $45.00 The person put in hours several days which span the rasies. 01/05/2010 10 hours (should be at $30/hr) 01/27/2010 5 hours (again at $30) 02/10/2010 10 hours (at $40/hr) 03/03/2010 5 hours (at $45/hr) I'm trying to write one SQL statement which will pull the hours, the cost per hour, and the hours*cost. The cost is the hourly rate last entered into the system so the cost date is less than the work date, ordered by cost date limit 1. SELECT person.id, person.name, work.hours, person_costs.value, work.hours * person_costs.value AS value FROM person INNER JOIN work ON (person.id = work.person_id) INNER JOIN person_costs ON (person.id = person_costs.person_id AND person_costs.date < work.date) WHERE person.id = 1234 ORDER BY work.date ASC The problem I'm having, the person_costs isn't ordered by date in descending order. It's pulling out "any" value (naturally sorted by record position) which matches the condition. How do I select the first person_cost value which is older than the work date? Thanks!

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  • MySQL table organization and optimization (Rails)

    - by aguynamedloren
    I've been learning Ruby on Rails over the past few months with no prior programming experience. Lately, I've been thinking about database optimization and table organization. I know there are great books on the subject, but I typically learn by example / as I go. Here's a hypothetical situation: Let's say I am building a social network for a niche community with 250,000 members (users). The users have the ability to attend events. Let's say there are 50,000 past/present/future events. Much like Facebook events, a user can attend any number of events and an event can have any number of attendees. In the database, there would be a table for users and a table for events. Somehow I would have to create an association between the users and events. I could create an "events" column in the users table such that each user row would contain a hash of event IDs, or I could create an "attendees" column in the events table such that each event row would contain a hash of user IDs. Neither of these solutions seem ideal, however. On a users profile page, I want to display the list of events they are associated with, which would require scanning the 50,000 event rows for the user ID of said user if I include an "attendees" column in the events table. Likewise, on an event page, I want to display a list of attendees for the event, which would require scanning the 250,000 user rows for the event ID of said event if I include an "events" column in the users table. Option 3 would be to create a third table that contains the attendee information for each and every event - but I don't see how this would solve any problems. Are these non-issues? Rails makes accessing all of this information easy, but I guess I'm worried about scale. It is entirely possible that I am under-estimating the speed and processing power of modern databases / servers / etc. How long would it take to scan 250,000 user rows for specific event IDs - 10ms? 100ms? 1,000ms? I guess that's not that bad. Am I just over-thinking this?

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  • How to use MySql date_add in Nhibernate?

    - by jalchr
    This really puzzled for hours, I searched all over the internet, but got no working solution. Can someone point where the problem is ... thanks ! I created my own dialect class public class MySQLDialectExtended : MySQLDialect { public MySQLDialectExtended() { RegisterFunction("date_add_interval", new SQLFunctionTemplate(NHibernateUtil.Date, "date_add(?1, INTERVAL ?2 ?3)")); } } Then I try to use it as follows: query.Append( " ( date_add_interval(D.ApprovalDate, 1, YEAR) < current_timestamp() < date_add_interval(D.RenewalDate, -1, YEAR) )"); It fails with following exception: NHibernate.Hql.Ast.ANTLR.QuerySyntaxException : Exception of type 'Antlr.Runtime.NoViableAltException' was thrown. near line 1, column 677 where the column number is at the end of the first 'YEAR' word. Edit: here is my configuration <property name="dialect">MyCompanyName.MySQLDialectExtended, MyCompanyName</property> <property name="hbm2ddl.keywords">none</property>

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  • MYSQL CASE WHEN PROBLEM

    - by user305270
    SELECT `profiles`.* FROM `profiles` INNER JOIN `friendships` ON `profiles`.id = `friendships`.(CASE WHEN friendships.profile_id = 1 THEN`friend_id` ELSE `profile_id` END) How can i make the inner join like profile.id = friendships.(here will select the one key that is needed) but it doesnt work. please help :P it cant be: `profiles`.id = (CASE WHEN friendships.profile_id = 1 THEN `friendships`.`friend_id` ELSE `friendships`.`profile_id` END)

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