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  • Emulating a transaction-safe SEQUENCE in MySQL

    - by Michael Pliskin
    We're using MySQL with InnoDB storage engine and transactions a lot, and we've run into a problem: we need a nice way to emulate Oracle's SEQUENCEs in MySQL. The requirements are: - concurrency support - transaction safety - max performance (meaning minimizing locks and deadlocks) We don't care if some of the values won't be used, i.e. gaps in sequence are ok. There is an easy way to archieve that by creating a separate InnoDB table with a counter, however this means it will take part in transaction and will introduce locks and waiting. I am thinking to try a MyISAM table with manual locks, any other ideas or best practices?

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  • Synchronizing MySQL databases

    - by Wasim
    Hi all, I have a maintanance problem synchronizing my MySQL data bases . These are the databases I have : My development DB : Here I make my curret development changes . Staging DB : I need to make all the changes I did in the development on it before using , currently I hold migration scripts for structure and data. Production DB : A production environment . Have to do exacly the same as the staging . My problem , is sync. the structure , and some of the data. This is really a very hard work to maintaine. Is there any technics , tools to do with MySQL . What is replication , is it good for my situation , how to use it . Thanks in advance ...

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  • SELECT set of most recent id, amount FROM table, where id occurs many times

    - by Jon Cram
    I have a table recording the amount of data transferred by a given service on a given date. One record is entered daily for a given service. I'd like to be able to retrieve the most recent amount for a set of services. Example data set: serviceId | amount | date ------------------------------- 1 | 8 | 2010-04-12 2 | 11 | 2010-04-12 2 | 14 | 2010-04-11 3 | 9 | 2010-04-11 1 | 6 | 2010-04-10 2 | 5 | 2010-04-10 3 | 22 | 2010-04-10 4 | 17 | 2010-04-19 Desired response (service ids 1,2,3): serviceId | amount | date ------------------------------- 1 | 8 | 2010-04-12 2 | 11 | 2010-04-12 3 | 9 | 2010-04-11 Desired response (service ids 2, 4): serviceId | amount | date ------------------------------- 2 | 11 | 2010-04-12 4 | 17 | 2010-04-19 This retrieves the equivalent as running the following once per serviceId: SELECT serviceId, amount, date FROM table WHERE serviceId = <given serviceId> ORDER BY date DESC LIMIT 0,1 I understand how I can retrieve the data I want in X queries. I'm interested to see how I can retrieve the same data using either a single query or at the very least less than X queries. I'm very interested to see what might be the most efficient approach. The table currently contains 28809 records. I appreciate that there are other questions that cover selecting the most recent set of records. I have examined three such questions but have been unable to apply the solutions to my problem.

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  • Using the MySql ASP.NET membership provider with existing users

    - by ScottBelchak
    I have been tasked with migrating an existing mature ASP.NET 2.0 web site to NHibernate, Mono and MySQL or postgres. I am somewhat confused as how the membership provider salts the passwords. If I make the switch and use the MySQL membership provider (outlined in this question) or AspSqlProvider, will the existing users be able to login? I guess it would be easier for me to ask: How the hell do I get access to the encryption key used by the ASP.NET membership provider that salts the passwords so that I can use the same one in a third party provider?

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  • How to strore Java Date to Mysql datetime...?

    - by user275843
    can any body tell me how can i store Java Date to Mysql datetime...? when i am trying to do so...only date is stored and time remain 00:00:00 in mysql date stores like this... 2009-09-22 00:00:00 i want not only date but also time...like 2009-09-22 08:08:11 please help me.... EDIT---- i am using JPA(Hibernate) with spring mydomain classes uses java.util.Date but i have created tables using handwritten queries... this is my create statement CREATE TABLE ContactUs (id BIGINT auto_increment, userName VARCHAR(30), email VARCHAR(50), subject VARCHAR(100), message VARCHAR(1024), messageType VARCHAR(15), contactUsTime datetime, primary key(id))TYPE=InnoDB;

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  • Advantages of SQLServer vs. MySQL for C#/.NET4 Cloud Applications

    - by Ed Eichman
    I am considering building several C#/.NET4 applications all using a central, cloud based database. In addition, several LAMP (MySQL) web shops will be accessing the cloud DB. MySQL is the database that I'm most familiar with, and my default selection for the cloud DB would be MySQL on Amazon or Joyent. However, I was wondering what development "extras" are available for SQLServer in VisualStudio 2010 that are not available for MySQL. Are there any "killer features" that should make me consider SQLServer instead of MySQL?

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  • Why this query is so slow?

    - by Silver Light
    This query appears in mysql slow query log: it takes 11 seconds. INSERT INTO record_visits ( record_id, visit_day ) VALUES ( '567', NOW() ); The table has 501043 records and it's structure looks like this: CREATE TABLE IF NOT EXISTS `record_visits` ( `id` int(11) NOT NULL AUTO_INCREMENT, `record_id` int(11) DEFAULT NULL, `visit_day` date DEFAULT NULL, `visit_cnt` bigint(20) DEFAULT '1', PRIMARY KEY (`id`), UNIQUE KEY `record_id_visit_day` (`record_id`,`visit_day`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 ; What could be wrong? Why this INSERT takes so long?

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  • How to SET tiggers 0 in MySQL?

    - by Grijesh Chauhan
    In my MySQL database I have some Triggers ON DELETE and ON INSERT. Some time I need to switched-off my some Triggers, And I have to DROP e.g. DROP TRIGGER IF EXISTS hostgroup_before_insert // and reinstall. Is there any shortcut to SET triggers hostgroup_before_insert = 0 like we have for foreign keys mysql> SELECT version(); +-------------------------+ | version() | +-------------------------+ | 5.1.61-0ubuntu0.10.10.1 | +-------------------------+ 1 row in set (0.00 sec) I am new learner and I could not find regarding this on web.

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  • Renamed MySQL table not renamed for INSERT queries?

    - by Austin Hyde
    After renaming one of my MySQL MyISAM tables from test_tablename to tablename, I have found that if I try to execute an INSERT (or REPLACE) query, I get the following message: 1146: Table 'dbname.test_tablename' doesn't exist I have triple-checked my database abstraction code, and verified this by running the query directly on the server. According to the MySQL server, the CREATE TABLE syntax is tablename, as expected, and when I run SHOW TABLES, it lists tablename as expected. Is there any reason for this to happen? More importantly, is there an easier way to fix this than dumping, dropping, re-creating, and reloading the table?

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  • Secure way to backup MySQL databases?

    - by user203538
    What is the best/secure way to backup a mysql database on windows server (2008)? I have "MySQL Administrator" but that requires that you save passwords for backup project. I'm not keen on doing as anyone gaining access to the server would then have easy access to the database. Can you do anything similar to SQL Server like using Windows authentication. If not what is the most secure (and practical) way of backups. Lastly, what are the privileges needed to backup a database? I have created a single user just for this task. Please advise.

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  • PHP: Simulate multiple MySQL connections to same database

    - by Varun
    An insert query is constantly getting logged in my MySQL slow query log. I want to see how much time the INSERT query is taking with 100 simultaneous insert operations(to the same table). So I need to simulate the follwoing. 500 different simultaneous connections from PHP to the same database on a mysql server, all of which are inserting a row(simultaneously) to the same table. DO I need to use any load testing tool? Or Can I simply write a PHP script to do this? Any thoughts?

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  • MySQL how to display data from two tables.

    - by gew
    I'm trying to display the username of the person who has submitted the most articles but I don't know how to do it using MySQL & PHP, can someone help me? Here is the MySQL code. CREATE TABLE users ( user_id INT UNSIGNED NOT NULL AUTO_INCREMENT, username VARCHAR(255) DEFAULT NULL, pass CHAR(40) NOT NULL, PRIMARY KEY (user_id) ); CREATE TABLE users_articles ( id INT UNSIGNED NOT NULL AUTO_INCREMENT, user_id INT UNSIGNED mNOT NULL, title TEXT NOT NULL, acontent LONGTEXT NOT NULL, PRIMARY KEY (id) ); Here is the code I have so far. $mysqli = mysqli_connect("localhost", "root", "", "sitename"); $dbc = mysqli_query($mysqli,"SELECT COUNT(*) as coun, user_id FROM users_articles GROUP BY user_id ORDER BY coun DESC LIMIT 1");

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  • overlay items from mysql

    - by user1285471
    I have several locations in tables in a mysql database which i want to have displayed as POI's, the table is too large and changes too frequently to use sql lite so i need to get the info from mysql. I have set up a mapView indicating the device location in mapview using an image at drawable, but i now need to ad the other locations from the database. Then when a user clicks on an item i need a popup with options to route there using google maps navigation, or view mobi site, phone, or email. I am new to android. Please assist. Have gone through the overlay tut but no indication on how to get the info from db. Is there a tut somwhere so i can see some example code to do this?

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  • Problem using mysql joins

    - by mariomario
    I'm fairly new to mysql and I have no idea if I'm heading in the right direction but I'm having trouble with a mysql query. I basically have a table of users id name ---- -------- 1 user1 2 user2 3 user3 4 user4 as well as a table of user attributes id userid attribute ---- ----- ------ 1 1 5 2 1 6 3 2 5 4 3 4 I want to be able to select users that have both the attribute 5 and the attribute 6, so in this case I want to return id name ---- -------- 1 user1 I tried using a join like this. SELECT u.id, u.name FROM users u LEFT JOIN attributes a ON (a.userid = u.id) WHERE a.attribute = 5 AND a.attribute = 6 But obviously that won't work, what is the best way of doing this?

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  • MySQL indexes - what are the best practises?

    - by Haroldo
    I've been using indexes on my mysql databases for a while now but never properly learnt about them. Generally I put an index on any fields that i will be searching or selecting using a WHERE clause but sometimes it doesn't seem so black and white. What are the best practises for mysql indexes? example situations/dilemas: If a table has six columns and all of them are searchable, should i index all of them or none of them? . What are the negetive performance impacts of indexing? . If i have a VARCHAR 2500 column which is searchable from parts of my site, should i index it?

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  • How to insert form data into MySQL database table

    - by Richard
    So I have this registration script: The HTML: <form action="register.php" method="POST"> <label>Username:</label> <input type="text" name="username" /><br /> <label>Password:</label> <input type="text" name="password" /><br /> <label>Gender:</label> <select name="gender"> <optgroup label="genderset"> <option value="Male">Male</option> <option value="Female">Female</option> <option value="Hermaphrodite">Hermaphrodite</option> <option value="Not Sure!!!">Not Sure!!!</option> </optgroup> </select><br /> <input type="submit" value="Register" /> </form> The PHP/SQL: <?php $username = $_POST['username']; $password = $_POST['password']; $gender = $_POST['gender']; mysql_query("INSERT INTO registration_info (username, password, gender) VALUES ('$username', '$password', '$gender') ") ?> The problem is, the username and password gets inserted into the "registration_info" table just fine. But the Gender input from the select drop down menu doesn't. Can some one tell me how to fix this, thanks.

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  • Find mininum unused value in mysql table

    - by splattru
    I have a MySQL table like this: +--------+-------+ + Server + Port + +--------+-------+ + 1 + 27001 + +--------+-------+ + 2 + 27002 + +--------+-------+ + 4 + 27004 + +--------+-------+ How you can see - here was 27003 port - but it was deleted some time ago (just for example). Is there some way to know the minimum value that is not used (higher than 27000 for example) in mysql table? Or there is no way and I need to make an separate table with all ports and column with "used" or "not used" ? Situation explanation: I am creating game hosting website, and I can use auto-increment for ports, but I will have a lot of deleted/unused ports after some time, and I want to use all of them before increasing port range. Thanks for your answers!

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  • Default datetime format in mySQL

    - by Davuz
    I'm coding to search data by compare datetime. In web form, user input value '2012-06-04' store in $_REQUEST['dateSearch']. I create datetime object from that: $dateObj = date_create_from_format("Y-m-d",$_REQUEST['dateSearch']); $dateParam = $dateObj->format("Y-m"); Then I use $dateParam in sql query to find data $sql = " SELECT * FROM `temp` as `t` WHERE `t`.`date` LIKE '$dateParam%' "; Everything is ok, but I'm not sure mySQL alway use only one datetime format "Y-m-d H:i:s". At here, $dateParam = $dateObj->format("Y-m"); I set default format is "Y-m". Is the default format never change? I don't want hard set format "Y-m-d H:i:s" in code, instead of, I think get format string from system to use is better. How do I get default datetime format string from mySQL???

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  • MySQL subquery and bracketing

    - by text
    Here are my tables respondents: field sample value respondentid : 1 age : 2 gender : male survey_questions: id : 1 question : Q1 answer : sample answer answers: respondentid : 1 question : Q1 answer : 1 --id of survey question I want to display all respondents who answered the certain survey, display all answers and total all the answer and group them according to the age bracket. I tried using this query: SELECT res.Age, res.Gender, answer.id, answer.respondentid, 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, CASE WHEN res.Age < 1 THEN 'age1' WHEN res.Age BETWEEN 1 AND 4 THEN 'age2' WHEN res.Age BETWEEN 4 AND 9 THEN 'age3' WHEN res.Age BETWEEN 10 AND 14 THEN 'age4' WHEN res.Age BETWEEN 15 AND 19 THEN 'age5' WHEN res.Age BETWEEN 20 AND 29 THEN 'age6' WHEN res.Age BETWEEN 30 AND 39 THEN 'age7' WHEN res.Age BETWEEN 40 AND 49 THEN 'age8' ELSE 'age9' END AS ageband 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 ageband ORDER BY res.Age ASC I was able to get the data but the listing of all answers are not present. Do I have to subquery SELECT into my current SELECT statement to show the answers? I want to produce something like this: ex: # of Respondents is 3 ages: 2,3 and 6 Question: what are your favorite subjects? Ages 1-4: subject 1: 1 subject 2: 2 subject 3: 2 total respondents for ages 1-4 : 2 Ages 5-10: subject 1: 1 subject 2: 1 subject 3: 0 total respondents for ages 5-10 : 1

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  • PHP+MYSQL Server Config

    - by Matias
    Hi guys, I am parsing an XML file with PHP and inserting the rows in a MYSQL database. I am using PHP simplexml_load_files to load the XML and a foreach to loop through the array and insert the rows into my database. It works perfectly fine with small files i am testing, but it comes to reality I need to parse a large 500mb XML file and nothing happens. I was wondering what was the right Php.ini config for this case ? I have a VPS Linux Cent OS, with 256 mb of dedicated Memory and MYSQL 5.0.5. I have also set php memory_limit = 256M (maximum of my server) Any suggestions, similar experiences will be greatly appreciated Thanks

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  • MySQL Update Trigger with Conditions

    - by user1760656
    I have a PHP app that inserts 'Pass', 'Fail' or 'NA' into fields TEST1, TEST2, TEST3... through TEST15. I have a field called OVERALL that needs to be automatically updated with 'FAIL' if any of the TEST1-TEST15 fields contains 'Fail'. I'm pretty sure I need to use a trigger containing the update statement and either CASE or IF, but I haven't been able to nail down the exact syntax. Can anyone please help a MySQL noob? I'm using MySQL Server version: 5.1.63-0+squeeze1 (Debian).

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