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  • mysql create table help with unique

    - by Matt
    I'm trying to create a table, and can't figure out how to assign two columns to be unique.. I know how to alter a table thats already created, but how do you do it in the create.. im after a create if not exist col1 TEXT, col2 TEXT, col3 TEXT unique(col1, col2) ^very rough basic but you get the idea

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  • mysql: Average over multiple columns in one row, ignoring nulls

    - by Sai Emrys
    I have a large table (of sites) with several numeric columns - say a through f. (These are site rankings from different organizations, like alexa, google, quantcast, etc. Each has a different range and format; they're straight dumps from the outside DBs.) For many of the records, one or more of these columns is null, because the outside DB doesn't have data for it. They all cover different subsets of my DB. I want column t to be their weighted average (each of a..f have static weights which I assign), ignoring null values (which can occur in any of them), except being null if they're all null. I would prefer to do this with a simple SQL calculation, rather than doing it in app code or using some huge ugly nested if block to handle every permutation of nulls. (Given that I have an increasing number of columns to average over as I add in more outside DB sources, this would be exponentially more ugly and bug-prone.) I'd use AVG but that's only for group by, and this is w/in one record. The data is semantically nullable, and I don't want to average in some "average" value in place of the nulls; I want to only be counting the columns for which data is there. Is there a good way to do this? Ideally, what I want is something like UPDATE sites SET t = AVG(a*a_weight,b*b_weight,...) where any null values are just ignored and no grouping is happening.

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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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  • 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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  • 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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  • 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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  • 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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  • 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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  • 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 - Separate Lastname,Firstname and CompanyName entries from a single column

    - by Decalmo
    I've got a column in a database which contains company names, and customer names all in one field... what I'd like to do is keep the CompanyName column completely intact, but wherever there is a comma in the CompanyName I'd like to take that information and populate it into a FirstName and LastName field. So that basically... Before: CompanyName: Big Company Inc Smith, John Sue, Maggie After: CompanyName: Big Company Inc Smith, John Sue, Maggie LastName: Smith Sue FirstName: John Maggie This one is pretty dang tricky for me... Any help is greatly appreciated!

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  • mysql table marked as crashed

    - by Phil Jackson
    I recently created a ajax based instant messaging application and after running for a while I got an error [table] is marked as crashed and should be repaired. How could this have happened and how do I go about preventing it happening again?

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  • Import excel files with image in php/mysql

    - by Marcel
    Hi all! I want to make an import script which allows users to upload their excel file (extension not important) to my php application. The application should reconize a list of items (so far so good). The difficulty in this case is that the excel files contain images...I've read information about phpexcel library but it does not say anything about images. Anybody ideas? Regards, Marcel

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  • MySQL DUMP as CSV

    - by swt83
    I've looked around and nothing seems to work: $file = '/path/to/file.csv'; $cmd = 'mysqldump DATABASE TABLE > '.$file.' --host=localhost --user=USER --password=PASS'; $cmd .= ' --lock-tables=false --no-create-info --tab=/tmp --fields-terminated-by=\',\''; exec($cmd); Everything I try creates an empty CSV file. Any ideas? Thanks much.

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  • Regex in MySql - replace between Tags including Tags

    - by user998163
    I have a text like: [lang_de]Content in German[/lang_de][lang_en]Content in English[/lang_en]. I want to replace all text between [lang_en] and [/lang_en] including the opening and closing language tag. This is my current regex: UPDATE wp_posts SET post_content = '" . addslashes(preg_replace("/[lang_en](.*)[\/lang_en]/", '', $row['post_content'])) . "' WHERE ID = " . $row['ID'] With this regex, I do not get a valid results. It also replaces in html tags and so on. What would be the correct regex?

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  • data in mysql show after barcode split and matches character

    - by klox
    i need some code for the next step..this my first step: <script> $("#mod").change(function() { var barcode; barCode=$("#mod").val(); var data=barCode.split(" "); $("#mod").val(data[0]); $("#seri").val(data[1]); var str=data[0]; var matches=str.matches(/EE|[EJU]).*(D)/i); }); </script> after matches..i want the result can connect to data base then show data from table inside <div id="value">...how to do that?

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