MySQL : Open-Source, Relational Database Management System

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How to put this particular constraint on this link table in MySQL? [duplicate]

I have the following three tables in MySQL: Store, Groups, StoreGroup. A store can belong to several groups. StoreGroup is the link table that records the groups a store belongs to. The Groups table ...
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1answer
28 views

Is there a difference between RANGE and LIST method for partitioning by consecutive integer values?

I have a table with a year column that has consecutive values -- 2000, 2001, and so on. It's a read-heavy MyISAM table, with 25+ million rows for every value of year and a comparable set inserted in ...
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1answer
34 views

MySQL consistent nonlocking reads vs. INSERT … SELECT

So, from my reading of the MySQL 5.5 documentation and some experiments I did with colleagues, I understand that the following is the case: With InnoDB tables, a simple SELECT statement (one that ...
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database result encoding changed

In my web site the content from the database is suddenly appearing in the wrong encoding! When I restart mysql the encoding is fixed, but after while it is again changed to the wrong encoding and I ...
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3answers
134 views

MySQL Explain has different row count than slow query log

I have this entry in slow query log: # User@Host: user[host] @ [ip] # Thread_id: 1514428 Schema: db Last_errno: 0 Killed: 0 # Query_time: 2.795454 Lock_time: 0.000116 Rows_sent: 15 ...
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41 views

Update query in a trigger

I have a configuration table: Table: refdatecol - id int(11) startdatecol varchar(100) enddatecol varchar(100) datecolTable varchar(100) This table holds the user configured column names ...
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4answers
195 views

Best practice for a Table with private columns

I have a table with user data, where most of the columns can be public or private (so it will be shown or not on the app) and every user can decide which fields to hide. So far I had a couple of ...
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27 views

Simple SELECT query doesn't return FALSE if no results

This is probably a simple fix, but I can't figure it out. This is the MySQL query I have: SELECT (`clockcards`.`date` IS NOT NULL) AS `clockedin` FROM `users` JOIN `clockcards` ON ...
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54 views

Finding the right MariaDB configuration

I’ve read several articles about how to configure MySQL/MariaDB, but now I’m kind of confused how to find the right values. Some articles suggest not choosing to high values, others recommend adapting ...
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1answer
278 views

Is it Possible to Recover Data from a BLACKHOLE table? [closed]

I had created table with engine BLACKHOLE basically the BLACKHOLE storage engine acts as a “black hole” that accepts data but throws it away and does not store it. Retrievals always return an empty ...
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40 views

How do I count the number of different child id's belonging to a parent record?

For instance I have two tables in a music database. Table album and table track. Each track record has (amongst other things), an album_id and an artist_id Each album record has a unique album_id ...
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17 views

MySQL grant privileges has no effect

I've executed the following queries: GRANT USAGE ON my_db.* TO my_user@127.0.0.1 IDENTIFIED BY 'pass'; GRANT ALL ON my_db.* TO my_user@127.0.0.1; GRANT SELECT, INSERT, UPDATE, DELETE ON my_db.* TO ...
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using ubuntu 14.04 when i use this command getting the error

just installed mysql server using sudo apt-get install mysql server when i try to display the database in terminal getting this type of error SHOW DATABASE; ERROR 1064 (42000): You have an error in ...
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18 views

mysql replication on windows server

How to setup replication(Master/slave) in MySQL 5.6 while both servers are windows based? All the things i have fond are Linux based replication. kindly someone help who experienced replication with ...
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1answer
31 views

Why/when does creating a mysql trigger require SUPER privileges?

I'm attempting to parse and understand what the MySQL doc says about when SUPER privileges are required for creating triggers. They say: If binary logging is enabled, CREATE TRIGGER might require ...
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49 views

group by clause without aggregate function

I've always assumed GROUP BY was designed specifically for aggregate functions and in all other circumstances you should use ORDER BY. For example, we have three tables: orders, shippers, and ...
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41 views

How to start mysqld with read-only data directory?

I'm trying to start MariaDB in a docker container, using a data directory from the host mounted read-only. MySQLd is of course shut down on the host. Unfortunately, even with adding the read_only flag ...
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1answer
39 views

MySQL Replication Lag Almost 23 Hours

I came into a new environment where the production DB was running on MySQL 4. Replication is usually about an hour behind but in the last few days it has been well over 24 hours behind. I'm not ...
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2answers
25 views

Creating a database with only MySQL command line?

The linux server on which I'm attempting to create a MySQL database has many difficult to work with permissions. My supervisor has tried to install MySQL Workbench on the server, but has been unable ...
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31 views

Tuning Mysql and Monitoring

I would like to know if anybody can point me towards a tool/way for MySQL database tuning ... Actualy the tunning of my.cnf is like below My database is in MyISAM | Mysql 5.1.73 key_buffer = 500M ...
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2answers
178 views

UPDATE query with JOIN taking forever

I'm not very good with databases so please keep in mind even if the solution sounds like something everyone would have already tried, please post it because I likely have not tried it and it would ...
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1answer
26 views

MySQL data transfer to different schema

We have two servers: one for the developper (me) and one for the tester. While working on the app, I sometimes make little changes in tables's schemas. (Like a new field, or a field type) I'm trying ...
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1answer
28 views

Change column without interrupting service

We need to change the data type of a column in a large table (~1.7 GiB) from VARCHAR(1024) to VARCHAR(512) in order to be able to create a secondary index over two columns. We're using MySQL 5.6 with ...
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21 views

Slow query log of wp_options WHERE autoload = 'yes'

Slow query log: # User@Host: # Query_time: 181.648376 Lock_time: 2.114138 Rows_sent: 1425838 Rows_examined: 1663532 SELECT option_name, option_value FROM wp_options WHERE autoload = 'yes'; Table ...
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32 views

MySQL Insert with Select

Trying to insert data to a table with values from different tables. INSERT INTO class_teachers_section(class_ref, teachers_ref, section_ref) select (select class.id as class_ref from class ...
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1answer
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Is it possible to import a single mysql database directory?

I am somewhat new to mysql. I created some databases recently and, to back them up, I just copied the folders with those database names in the mysql data directory (i.e containing only db.opt, .frm, ...
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3answers
193 views

MySQL buffer pool usage + high load

We've got a quite powerful server: HP ProLiant DL360p Gen8, 2xIntel Xeon E5-2630 2.30GHz, 128GB of RAM. The whole data set should fit in memory: mysql> SELECT ...
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2answers
57 views

Should I drop a foreign key if I use a soft delete?

"ON UPDATE" scenario never happens in my application. As soft delete is used, "ON DELETE" cascade and restrict scenario never happen as well now. Then, should I just drop foreign key because I have ...
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Mysql query with LIMIT much slower under RDS (5.6) than old 5.1 system

We inherited an old legacy system running on mysql 5.1, and moved it to RDS running 5.6. One query is running much slower - it can take up to 20 minutes to run, where previously it took only a few ...
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1answer
26 views

MySQL InnoDB table accepts Non-Existent Foreign Key

Using EasyPHP 14.1 VC11 and phpMyAdmin (4.1.4) to create a website project in my home computer. The MySQL version is 5.6.15 according to the EasyPHP administration page. Working on Windows 7 64-bit. ...
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1answer
24 views

Mysql INSERT INTO .. ON DUPLICATE KEY UPDATE

I'm trying to do the following query in mysql 5.5 INSERT INTO countingTable( image_count, article_id ) SELECT COUNT( article_id ) AS sum, article_id FROM imageTable ON DUPLICATE KEY UPDATE ...
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Error stored procedure Mysql

I have a table and every month need to delete data for new data are included. I made a stored procedure to automate this process. This table has about 3 million lines in a monthly period. This can ...
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Do MySQL optimizations hold for MariaDB also?

I am a developer who will be starting a new project soon in which database performance will be crucial. The current candidate for the backend is MariaDB. I have worked with MySQL and MariaDB before in ...
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23 views

Restore data from MYSQL Bin log

I am trying to restore some data from mysql bin log file. But when it encounter some special characters, query gets break and I am not able to continue after that. Is there any way to handle special ...
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61 views

MySQL select with left join query

I have following code. select class.name as classname, class.hours as hours, teachers.first_name as teacherFirstName, teachers.last_name as teacherLastName from teachers,class left join ...
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24 views

Loop through all users in MySQL and add REQUIRE SSL flag

How do I loop through all users (we have > 3000) in a MySQL database, and add the REQUIRE SSL flag to the every account? I don't want to modify the existing users permissions, host, or password, ...
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1answer
58 views

Understanding JOINs and why the syntax works the way it does

Heyo, I'm confused as to how this works: UPDATE original SET price=(SELECT price FROM new WHERE new.id=original.id) WHERE id IN (SELECT id FROM new); What it does is updating an original table ...
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1answer
34 views

How to run mssql server dependent application to mysql workbench [closed]

I am very new in mysql workbench. I have created an application in c# which uses sql server 2008 r2 database. Now i have migrated my database on mysql workbench. i want to run my application now. My ...
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1answer
128 views

mysql privilege to kill processes of other users

I have a percona mysql database. The version is 5.5.29-29.4-log. I have created a user called admin which should be able to kill processes initiated by other users, i.e worker. GRANT SELECT, ...
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2answers
245 views

Changing data type from mediumint to int without downtime

My current table is using MEDIUMINT for ID column ‘primary key auto increment’. The current table records soon will reach the maximum value for mediumint which is 8388607. That being the case, I need ...
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24 views

move content from one table to another table and add a new value

I need to move content from one table to another table, this part is done: INSERT INTO `insc_mwc` (`nome`,`empresa_idempresa`,`cat_mwc_idcat`,`points_pontos`,`n_registo`) SELECT ...
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25 views

How to update MySQL with CentOS 6 in most unintrusive way - in regard to perl and PHP packages? [closed]

For my few hobby projects (web games + forums) I have been using CentOS 5 (then 6) with Drupal and PostgreSQL plus few custom PHP and Perl scripts written by mysef. Since PostgreSQL version delivered ...
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1answer
23 views

MySQL: can a table get stuck in the table cache?

I've asked this question on the ServerFault stackexchange, someone directed me here. I'm a PHP developer and am responsible for a set of PHP scripts that run on a shared host running FreeBSD, that ...
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3answers
43 views

Redesign basic Mysql storage architecture

We are a small Internet provider and we are storing all our clients traffic data in a MySQL database (MyISAM). We insert data every few minutes in three tables like this: capture_table ---------- ...
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26 views

Show weeks based on the date range

I have a table that has Start Date and End Date. I am very new to MySQL, I was wondering what MySQL query can I use to get all the data from Monday to Friday and show in which week it falls. like ...
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1answer
24 views

MySQL cluster replication: Slave cluster should not store any data except data replicated from master cluster?

I am researching MySQL cluster replication. I read a section "We assume that the slave server or cluster is dedicated to replication of the master, and that no other data is being stored on it" in ...
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Percona MySQL LDAP authentication fails through .NETmysql connector

Basically MySQL uses its native authentication, where the username and passwords are stored in mysql.user table. MySQL authenticates user against the credentials stored in mysql.user table. Our ...
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score ranking no tie, if tie order by score submit date

I have a very simple MySQL table where I save highscores. It looks like that: Id Name Score SubmitDate So far so good. The question is: How do I get what's a users rank EVEN THEIR SCORE IS ...
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51 views

How to loop SQL query in mysql?

I have a SQL query as following: SET @thedate := CURDATE(); create temporay table tmp1( ... where thedate=@thedate ); create temporay table tmp2( ... where thedate=@thedate ); delete from tbl1; ...
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52 views

MYSQL Query - Unexpected result in text messaging database

On a text messaging database I have built, I am trying to return the total amount of messages a user has sent and the total number of messages a user has received. I have the following code: SELECT ...