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  • MYSQL and the LIMIT clause

    - by Lizard
    I was wondering if adding a LIMIT 1 to a query would speed up the processing? For example... I have a query that will most of the time return 1 result, but will occasionaly return 10's, 100's or even 1000's of records. But I will only ever want the first record. Would the limit 1 speed things up or make no difference? I know I could use GROUP BY to return 1 result but that would just add more computation. Any thoughts gladly accepted! Thanks

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  • PHP/Mysql issues

    - by queryne
    Php/my sql newbie question. I have a database I've imported into my local phpmyadmin. However it seems I can't access it from my a php application. The connection string seems right and when i try to authenticate user credentials to access database information, no problems. However authenticate everyone and knows when i put in fake credentials. Still it won't pull any other information from the database. For instance, once a users login they should see something like, "Hello username"... that kind of thing. At this point I see "Hello" without the username. Any ideas what i might be missing?

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  • Next and Previous MySQL row based on name

    - by NightMICU
    Hi everyone, I have a table with details on personnel. I would like to create a Next/Previous link based on the individual's last name. Since personnel were not added in alphabetical order, selecting the next or previous row based on its ID does not work. It is a hefty table - the pertinent fields are id, name_l, and name_f. I would like to order by name_l, the individuals' last name. How would I go about accomplishing this task? Thanks!

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  • Efficient algorithm for Next button on a MySQL result set

    - by David Grayson
    I have a website that lets people view rows in a table (each row is a picture). There are more than 100,000 rows. You can view different subsets of the rows, and you can view them with different sort orders. While you are viewing one of the rows, you can click the "Next" or "Previous" buttons to go the next/previous row in the list. How would you implement the "Next" and "Previous" features of the website? More specifically, if you have an arbitrary query that returns a list of up to 100,000+ rows, and you know some information about the current row someone is viewing, how do you determine the NEXT row efficiently? Here is the pseudo-code of the solution I came up with when the website was young, and it worked well when there were only 1000 rows, but now that there are 100,000 rows I think it is eating up too much memory. int nextRowId(string query, int currentRowId) { array allRowIds = mysql_query(query); // Takes up a lot of memory! int currentIndex = (index of currentRowId in allRowIds); // Takes time! return allRowIds[currentIndex+1]; } While you are thinking about this problem, remember that the website can store more information about the current row than just its ID (for example, the position of the current row in the result set), and this information can be used as a hint to help determine the ID of the next row. Edit: Sorry for not mentioning this earlier, but this isn't just a static website: rows can often be added to the list, and rows can be re-ordered in the list. (Much rarer, rows can be removed from the list.) I think that I should worry about that kind of thing, but maybe you can convince me otherwise.

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  • List hits per hour from a MySQL table

    - by Axel
    I am trying to work out the hits per hour from a database. Data basically is stored as follows (with other columns) : Table Name: Hits ============================ VisitorIP TIMESTAMP ---------------------------- 15.215.65.65 123456789 I want to display total hits per hour (within the last 6 hours ) including the hours that has no hits. Example of the output: // Assuming now : 21:00 21:00 - 0 hits 20:00 - 1 hits 19:00 - 4 hits 18:00 - 0 hits 17:00 - 2 hits 16:00 - 3 hits i would love to get the data as array, Please note that the stored date is in UNIX time stamp format. and there may be some hours without any hits! Thanks

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  • Validating Login / Changing User settings / Php Mysql

    - by Marcelo
    Hi everyone, my questions are about login, and changing already saved data. (Q1) 'Till now I've only saved input in the tables of the database (registration steps), now I need to check if the input (login steps), are the same of my table in database, in fact I have 3 types of users, then I'll have to check 3 kind of tables. Then if the input data matches with one of those 3 tables I will redirect the user to his specific area. I'm thinking about saved the submitted data $login=$_REQUEST['login']; and $password=$_REQUEST['password']; and compare with the login column in the database. Then if the login matches, I'll compare the password submitted with the one in the row, not in the column. But I don't know how to do this search and comparison,neither what to use. Then if both matches I'll redirect the user. Else I'll send an login error message. (this I know how to do) (Q2) What if need to change an already saved user ? For example to change an email address. My changing user's data web page is exactly the same like the registration user web page. Can I load the already saved options and values of registration (table user for example). Then the user will change whatever he thinks it's necessary, and then when he submits the new information, they would not create a new row in my table, but just be overwritten the old information? How can I do this? Sorry for any mistake in English, and Thanks for the attention.

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  • mysql : Recieve data only per months

    - by Tristan
    Hello, few times ago, i asked how to do to display datas per month, i must told a bad explanation because i just figured out that it's not what i want : Here's what I got : $req1 = ... AND v.date > (DATE_SUB(CURDATE(), INTERVAL 2 MONTH)) AND v.date < (DATE_SUB(CURDATE(), INTERVAL 1 MONTH)) $req2= ... AND v.date > (DATE_SUB(CURDATE(), INTERVAL 3 MONTH)) AND v.date < (DATE_SUB(CURDATE(), INTERVAL 2 MONTH)) But the problem, imagine that today you are the 10th june, it's going to calculate ALL the data between the 10 june to the 10 may then the 10 may until the 10 april... But what i want is data : from 1st may to 1 st june, from 1st june to 1st july... do you see what i mean ? thank you ;)

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  • Mysql Performance Question - Essentially about normalizing efficiency

    - by freqmode
    Hi there. Just a quick question about database performance. I'll outline my site purpose below as background. I'm creating a dictionary site that saves the words users define to a database. What I'm wondering is whether or not to create a words table for each user or to keep one massive words table. This site will be used for entire schools so the single words table would be massive! The database structure is as follows: A user table with: User_ID PRIMARY KEY Username First Last Password Email Country Research Standings SendInfo Donated JoinedOn LastLogin Logins Correct Attempts Admin Active And one word table with: User_ID PRIMARY KEY Word Vocab Spell Defined DefinedAttempted Spelled SpelledAttempted Sentenced SentencedAttempted So what I'm asking is , performance-wise, should I create a new table for each user when they join the site - each user could have hundreds or thousands of words over time? Or is it better to have one massive table with thousands and thousands of records and filter by User_ID. I don't think I'll perform many table joins. My gut feeling is to create a new table for each user, but I thought I'd ask for expert advice! Thanks in advance.

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  • I'm looking for a constraint to prevent the insert of an empty string in MySQL

    - by Marga Keuvelaar
    Ok, in this question I learned how to prevent the insert of a NULL value. But, unfortunately, an empty string is being inserted anyway. Apart from preventing this on the PHP side, I'd like to use something like a database constraint to prevent this. Of course a check on the application side is necessary, but I'd like it to be on both sides. I am taught that whatever application is talking to your database, it should not be able to insert basically wrong data in it. So... CREATE TABLE IF NOT EXISTS tblFoo ( foo_id int(11) NOT NULL AUTO_INCREMENT, foo_test varchar(50) NOT NULL, PRIMARY KEY (foo_id) ); Would still allow me to do this insert: INSERT INTO tblFoo (foo_test) VALUES (''); Which I would like to prevent.

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  • PHP MYSQL Add up number of entries in single table and display in HTML

    - by Derek
    I have a table called activities which contains a number of activities for projects (for example 6 activities are related to one project). On a manage projects page, you can see the projects, and I have one column which needs to display the number of tasks associated with the project (in that particular row). So basically, I need a query or PHP calculation that can add up the number of tasks for the project and then display this number dynamically! I know exactly what I need, just do not know how to implement it. Any help is much appreciated! Thanks.

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  • batch update mysql table

    - by Yang
    I have a table with a column called time, "HH:MM:SS". How can I do a batch update so that the value increment by 1 hour? Is it something like: update <table_name> set <time_column> = <time_column> + 3600 where ...

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  • Strange behavior of MySQL UPDATE query in PHP?

    - by Prashant
    When I am executing following query then its not updating views column by 1 instead sometimes its updating it by 2 or 3. Say currently views count is 24 then after executing this query it becomes 26 or sometimes its 27. $views = $views + 1; $_SQL = ''; $_SQL = 'UPDATE videos SET views = '.$views.' WHERE VideoId= "'.$videoid.'";'; @mysql_query($_SQL); I am not getting why this is happening, am I missing something or the query is executing 2 times automatically? Please help me to figure out the issue. Thanks

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  • Syntax for "RETURNING" clause in Mysql PDO

    - by dmontain
    I'm trying to add a record, and at the same time return the id of that record added. I read it's possible to do it with a RETURNING clause. $stmt->prepare("INSERT INTO tablename (field1, field2) VALUES (:value1, :value2) RETURNING id"); but the insertion fails when I add RETURNING. There is an auto-incremented field called id in the table being added to. Can someone see anything wrong with my syntax? or maybe PDO does not support RETURNING?

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  • define mysql indexing

    - by Bharanikumar
    Hi Am not sure, This is the right place to post this question , But in our stack overflow only am getting clear vision solutions , What is indexing and what is fulltext , for the above both questions i know the ans, but i cant expose that ans in the exact way to the interviewer , (indexing means somthing like index in book) (fulltext means for search string), Can please give me very simple defination for this questions , Advance thanks

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  • What is wrong with this trigger in mysql?

    - by Jimit
    Hi all, Below is trigger that I need to create but It is not getting created.Please any buddy can explain me what is wrong with this trigger ? Help me please. DELIMITER $$ CREATE TRIGGER property_history_update AFTER UPDATE ON `properties` FOR EACH ROW BEGIN IF OLD.ListPrice != NEW.ListPrice THEN INSERT INTO `property_history` SET ListingKey=OLD.ListingKey,ListPrice = NEW.ListPrice, ListingStatus = OLD.ListingStatus,LastUpdatedTime = NEW.LocalLastModifiedOn; END IF; END$$ DELIMITER ;

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  • (mySQL) Unable to query 2 tables properly for data

    - by Devner
    I have 2 tables. One is 'page_links' and the other is 'rpp'. Table page_links is the superset of table rpp. The following is the schema of my tables: -- Table structure for table `page_links` -- CREATE TABLE IF NOT EXISTS `page_links` ( `page` varchar(255) NOT NULL, `page_link` varchar(100) NOT NULL, `heading_id` tinyint(3) unsigned NOT NULL, PRIMARY KEY (`page`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; -- -- Dumping data for table `page_links` -- INSERT INTO `page_links` (`page`, `page_link`, `heading_id`) VALUES ('a1.php', 'A1', 8), ('b1.php', 'B1', 8), ('c1.php', 'C1', 5), ('d1.php', 'D1', 5), ('e1.php', 'E1', 8), ('f1.php', 'F1', 8), ('g1.php', 'G1', 8), ('h1.php', 'H1', 1), ('i1.php', 'I1', 1), ('j1.php', 'J1', 8), ('k1.php', 'K1', 8), ('l1.php', 'L1', 8), ('m1.php', 'M1', 8), ('n1.php', 'N1', 8), ('o1.php', 'O1', 8), ('p1.php', 'P1', 4), ('q1.php', 'Q1', 5), ('r1.php', 'R1', 4); -- Table structure for table `rpp` -- CREATE TABLE IF NOT EXISTS `rpp` ( `role_id` tinyint(3) unsigned NOT NULL, `page` varchar(255) NOT NULL, `is_allowed` tinyint(1) NOT NULL, PRIMARY KEY (`role_id`,`page`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; -- -- Dumping data for table `rpp` -- INSERT INTO `rpp` (`role_id`, `page`, `is_allowed`) VALUES (3, 'a1.php', 1), (3, 'b1.php', 1), (3, 'c1.php', 1), (3, 'd1.php', 1), (3, 'e1.php', 1), (3, 'f1.php', 1), (3, 'h1.php', 1), (3, 'i1.php', 1), (3, 'l1.php', 1), (3, 'm1.php', 1), (3, 'n1.php', 1), (4, 'a1.php', 1), (4, 'b1.php', 1), (4, 'q1.php', 1), (5, 'r1.php', 1); WHAT I AM TRYING TO DO: I am trying to query both the above tables (in a single query) in such a way that all the pages from page_links are displayed along with the is_allowed value from rpp for a particular role. For example, I want to get the is_allowed value of all the pages from rpp for role_id = 3 and at the same time, list all the available pages from page_links. A clear example of my expected result would be: page is_allowed role_id ---------------------------------------- a1.php 1 3 b1.php 1 3 c1.php 1 3 d1.php 1 3 e1.php 1 3 f1.php 1 3 g1.php NULL NULL h1.php 1 3 i1.php 1 3 j1.php NULL NULL k1.php NULL NULL l1.php 1 3 m1.php 1 3 n1.php 1 3 o1.php NULL NULL p1.php NULL NULL q1.php NULL NULL r1.php NULL NULL One more example of my desired result could be achieved by doing a LEFT JOIN rpp ON page_links.page = rpp.page but we need to omit using role_id = 3 (or any value) to be able to get that. But I do want to specify the role_id as well and get the results. I need the query to be able to get this result. I would appreciate any replies that could help me with this. If you can suggest me any changes as well to the table(s) design to be able to achieve the desired result, that's good as well. Thanks in advance.

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  • Mysql partition error?

    - by drake
    I have a kinda table like this: CREATE TABLE test ( id MEDIUMINT NOT NULL AUTO_INCREMENT, user VARCHAR(30), time VARCHAR(30), status VARCHAR(30), origin VARCHAR(30), PRIMARY KEY (id) ) ENGINE=MyISAM; PARTITION BY RANGE(id) ( PARTITION p0 VALUES LESS THAN (500000), PARTITION p1 VALUES LESS THAN (1000000), PARTITION p2 VALUES LESS THAN (1500000), PARTITION p3 VALUES LESS THAN (2000000), PARTITION p4 VALUES LESS THAN (2500000) ) I have Three questions: 1) I have here an #1064 error; 2) How can i set split test.user as alphabetic range in partition; 3) How can i check that the partition was successful;

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  • Optimizing Mysql to avoid redundancy but still have fast access to calculable data

    - by diglettpotato
    An example for the sake of the question: I have a database which contains users, questions, and answers. Each user has a score which can be calculated using the data from the questions and answers tables. Therefore if I had a score field in the users table, it would be redundant. However, if I don't use a score field, then calculating the score every time would significantly slow down the website. My current solution is to put it in a score field, and then have a cron running every few hours which recalculates everybody's score, and updates the field. Is there a better way to handle this?

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  • Java/MySQL: Working with data in classes

    - by skiwi
    What is the best way to deal with accessing/modifying tables in a database? I have read about the Data Access Object approach, but none of the resources I have found so far indicate a clear implementation of it. So assume you have a database with a table called accounts that has columns id, name, password and email. How would you properly access it within Java? I mean most people know how to do SQL statements, but that is not really the point. I hope people here can be of help. Regards.

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  • MySQL query puzzle - finding what WOULD have been the most recent date

    - by Hank
    I've looked all over and haven't yet found an intelligent way to handle this, though I feel sure one is possible: One table of historical data has quarterly information: CREATE TABLE Quarterly ( unique_ID INT UNSIGNED NOT NULL, date_posted DATE NOT NULL, datasource TINYINT UNSIGNED NOT NULL, data FLOAT NOT NULL, PRIMARY KEY (unique_ID)); Another table of historical data (which is very large) contains daily information: CREATE TABLE Daily ( unique_ID INT UNSIGNED NOT NULL, date_posted DATE NOT NULL, datasource TINYINT UNSIGNED NOT NULL, data FLOAT NOT NULL, qtr_ID INT UNSIGNED, PRIMARY KEY (unique_ID)); The qtr_ID field is not part of the feed of daily data that populated the database - instead, I need to retroactively populate the qtr_ID field in the Daily table with the Quarterly.unique_ID row ID, using what would have been the most recent quarterly data on that Daily.date_posted for that data source. For example, if the quarterly data is 101 2009-03-31 1 4.5 102 2009-06-30 1 4.4 103 2009-03-31 2 7.6 104 2009-06-30 2 7.7 105 2009-09-30 1 4.7 and the daily data is 1001 2009-07-14 1 3.5 ?? 1002 2009-07-15 1 3.4 && 1003 2009-07-14 2 2.3 ^^ then we would want the ?? qtr_ID field to be assigned '102' as the most recent quarter for that data source on that date, and && would also be '102', and ^^ would be '104'. The challenges include that both tables (particularly the daily table) are actually very large, they can't be normalized to get rid of the repetitive dates or otherwise optimized, and for certain daily entries there is no preceding quarterly entry. I have tried a variety of joins, using datediff (where the challenge is finding the minimum value of datediff greater than zero), and other attempts but nothing is working for me - usually my syntax is breaking somewhere. Any ideas welcome - I'll execute any basic ideas or concepts and report back.

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