MySQL : Open-Source, Relational Database Management System

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Optimize Query in MySQL

I've following tables with respective fields 1) wi_individual_g(ind_id,ind_is_recepient,ind_deleted,ind_district_id,...) - Around 200K data 2) wi_individual_p(ind_id,prg_id,...) Around 250K data 3) ...
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Use ID from another mysql database?

I have a mysql database for form submission (written in PHP) data and a mysql database for CRM (using X2CRM) on the same server. When a form is submitted on my website the POSTed data of the form ...
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Allow only parent DELETE cascade to delete child rows

I have a Product database with the following components: ProductOptions is a list of option names for each Product, ProductVariants is a list of variants for each Product and ProductVariantOptions is ...
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Multi tenant database: Join table between 3 tables (user-role-company)

When designing a multi-tenant design i face this problem: One User can have multiple Roles, one Role can have Users (m-n) One user can be part of multiple Companies (organizations) and Vice-Versa ...
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Slave executing queries with different charset

I need to change a database charset because of this issue and I solved my issue in staging environment with the SQL command ALTER TABLE `articles` CONVERT TO CHARACTER SET utf8 COLLATE ...
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SELECT COUNT(*) expensive query mysql?

I have following query: SELECT COUNT(*) AS `numrows` FROM (`phppos_items`) WHERE `deleted` = 0 explain: mysql> explain SELECT COUNT(*) AS `numrows` -> FROM (`phppos_items`) ...
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Select range of non-identical date from different table

On MySQL5 with innoDB, I have sensor data in multiple tables, all with an ID and a DATETIME field, like so (two tables shown, but there are more). The IDs and DATETIMEs are not identical between ...
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How we resolve Mysql Enterprise online backup error with “CORRUPT LOG RECORD FOUND” log error

I have configured my production MySQL database with MySQL Enterprise "online Backup" option. The configuration was went through successfully. When the assigned scheduler is try to take backup then i ...
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how effective creating 2 database with same content?

I'm in a dilemma if creating redundant database will speed up the access considering only the CRUD factor. Is it effective to create a dedicated DB for creating/updating/deleting records and a ...
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Why is MySQL not saving inserted data?

So I have the following insert statement that I run through MySQL Workbench: INSERT INTO PeakOnlineCount (time_stamp, LocationId, Count) values ('2015-03-26', 0, 1) If I run the following query: ...
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LEFT JOIN DEFAULT NULL VALUE

I had query simplified like this : SELECT a.id, a.name, b.* FROM a LEFT JOIN b ON a.id=b.id Which b is from group concat select (very dynamic column). Sometime there are 3 column in b, sometime ...
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MySQL silently replaces UTF chars with literal question marks

I'm experiencing a situation similar to this SO question i.e. I'm working with a legacy database which has UTF8 content in latin1 tables (pretty ugly I know). Now I'm getting new data from a new ...
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mysql upgrading from 5.1 --> 5.6 do I have to do mysqldump before upgrade?

I was reading this document: http://dev.mysql.com/doc/refman/5.5/en/upgrading-from-previous-series.html It says when upgrading from mysql 5.1 to do a mysqldump and then a reload. Is there anyway ...
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How to keep updates (diffs) of some entity in the database

What is the best way to keep updates (diffs) of the some entity in the database? At StackOverflow we can edit questions and answers. And then we can look at any revision of the question or answer we ...
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26 views

Why can't I use a cname/alias in the permissions table?

At work we have a usual setup with web server(apache) and database server(mysql). From time to time there is the need to migrate the web stuff to a new server. Lets say their a records are dull and ...
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MySQL Date field: filter by LIKE vs MONTH()

I have a CRON task that needs to extract customers with birthday in a given month, from a MySQL INNODB table. The birthday field is indexed and of type DATE. I can query the customers table by either ...
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How to use a trigger to only insert one row

I am doing a third year project using an intel galileo that reads an RFID card, and signs a student into a class, and I am using multiple tables. I have nearly completed it as all reads are been ...
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What are Client Access Profiles and what are they used for?

Can someone please explain to me what Client Access Profiles are, and what they are used for? I have not able to find 1 single thing about them online in the past week.
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How to restore mysql database in XAMPP using backup of mysql folder?

I have a backup of the entire xampp/mysql folder. How can I use it to recover my old db on a fresh installation of XAMPP? Simply copying the old xampp/mysql folder to new xampp leads to mysql errors ...
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Is it possible to ADD 2 EER model from 2 differents database in the same editor screen in MySQL Workbench?

I am using MySQL workbench to visualize a EER model form one database, lets says db1. It is a 166 tables database. Then I have another database, that interacts with db1, that has 10 tables. So I have ...
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GROUP BY parentId and MAX childId

My tables are below: crm_conversions crm_messages_of_conversions crm_receivers_of_messages I want to get all of conversions of an user with only last message. I'm trying to get with the query: ...
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MySql Replicate different tables to different database

I have Database1 on server1 and Database2,Database3 on server2. Database1 has two tables T1, T2. I want to replicate T1 on Database2 and T2 on Database3. How can I accomplish it? I googled but only ...
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difference between phpmyadmin and php PDO

I'm running a query in Phpmyadmin and also execute the same query with php PDO but results are not equal. What could be wrong ? This is query : SELECT dim_date_key as date ,dim_jdate_key as jdate, ...
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MySQL Replication Lag Check

we are about to replicate our database servers into several slaves in different physical locations. The company which is doing replication for us, has asked to give them a sql select statement on ...
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How to Solve ERROR 1064 (42000)?

DROP PROCEDURE IF EXISTS proc_x; DELIMITER # CREATE DEFINER=`root`@`localhost` PROCEDURE proc_x(sequel CHAR) proc_main:BEGIN SET @SQL = CONCAT(@sequel); PREPARE stmt FROM @SQL; EXECUTE stmt; ...
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mariadb / mysql wont change table_cache / table_open_cache

I've configured my i7 64gb ssd server with centos7 with the following my.cnf [mysqld] key_buffer = 12M max_allowed_packet = 16M table_cache = 4096 table_open_cache = 4096 table_definition_cache = ...
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data calling from one page to another? [migrated]

Hey guys i have a question. I am trying to set up something for my insurance website. I want to setup a capture page where the user inputs everything related to their vehicle and their information and ...
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3answers
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How to interract with my database? [closed]

I am generally new to Databases, and I have a MySQL server with several tables which have a unique ID that is connecting them all. I am about to populate the db with data from external resources ...
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MySQL General error: 126 Incorrect key file for table '/tmp/#sql_27e6_0.MYI'; try to repair it'

I have a table in MySQL with ~2,000,000 rows. When I try to select all records, it exhausts the system's memory and I get an error about memory exhaustion back. When I try to use the MySQL LIMIT and ...
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MYSQL Get column group with different values on other column

I have the following table: week status ------- ------ 102014 1 102014 1 102014 1 112014 2 112014 2 112014 2 122014 2 122014 0 122014 0 132014 1 ...
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User, host, and privileges

In a MySQL 5.6 database I found one user 'foo'@'10.0.0.2' with ALL PRIVILEGES. I also discovered an user 'foo'@'10.0.0.3' granted only USAGE privileges. Does this second user definition make sense? ...
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Optimizing an AVG / GROUP BY query

Here is the query: SELECT p.domain_id AS comp, AVG(IFNULL(p.position, 50)) as AVG, p.date AS period FROM userdomain ud LEFT JOIN userdomainexpression ude ON ude.userdomain_id=ud.id ...
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Replication Issue - Changing the replication-do-db filter

I have a server that someone has setup which are acting as a master on both database. Since they have been configured as both master on the same database, changes one on end has caused all sorts of ...
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Most efficient way to set up a database handling millions of links? [closed]

I'm looking at making a site that will potentially have up to a million users, and each user will have hundreds/thousands of links connected to a set of sites, as well as other info. I'm using mysql ...
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Does MySQL Backup Restore affect Master-Master Replication

Hello I got some problems with a MySQL shemas and it seems that the schemas got deleted for an unknown reason. I try to find in the binlog for more information of this but I didn't find the way to see ...
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Slow database drop in mysql

Just installed a new 24 core server and it is noticeably slower when doing truncates and drops. Example: $ mysql -u root lmcdental_test2 Reading table information for completion of table and column ...
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I have a DB that is locking up from numerous updates to a table: Should I convert it from MyISAM to InnoDB?

FYI: I don't believe this is a duplicate question, I've looked and most are general questions with vague answers. See more specifics below: Currently a database I am in charge of locks up every once ...
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Maximum possible memory usage: 23.6G (785% of installed RAM)

I have a virtualized 32bits Server for Mysql (RAM : 115 Go). I am trying to optimize with mysqltuner and I get this : >> MySQLTuner 1.1.1 - Major Hayden <major@mhtx.net> >> Bug ...
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How should I store image, text type files in mysql?

I came across some answers mentioning the "disasters" of storing files outside database and saving the path inside database. I've also noticed dozens of answers about storing images- which suggest to ...
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Alias of Subquery not working

I have been trying to get an order by to work correctly with an aggregate function. i.e. order by (bp + points) I also try adding these as a total amount from the following query however. If I try ...
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Percona Master-Master lag issues

I have 2 servers with master-master replication using Percona MySQL 5.6 and I am having replication lag in the second server: db-02, however db-01 never had a lag situation. What could be causing ...
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Clustering MySQL with InnoDB engine

I have a MySQL single server setup with all tables using the InnoDB engine (because I need support for foreign keys). As response times are getting longer, I now believe I need to create a cluster of ...
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CONCURRENT SELECT's SLOW … LOCK IN SHARE MODE

My Table has 25 Million rows total and 6 million rows satisfying below where clause. Select 1: select max(stamp) from Table where type = "string" LOCK IN SHARE MODE ; 6000+ seconds Select 2: ...
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1answer
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Are there any risks in running 'flush hosts'?

Due to an error in my code I got my PC blocked from an active production DB (too many connection errors). The error calls for me to use 'flush hosts' in order to reset the host cache. Are there any ...
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How to get mysql view definitions?

Show create view viewName does not display correctly formatted text. How can I get the correctly-formatted SQL? For example, I created a view like create view v1 as select * from mysql.uer, but it ...
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Will 'sleeping' connections open files other than the socket in MySQL?

Recently, in our MySQL replication setup, the replication slave crashed due to 'too many open files' error. We brought it backup, but trying to figure out what caused the unexpected hike in the number ...
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Innobackupex - Safe and recommended value for lock-wait-timeout?

I am using xtrabackup tool as a backup, can someone please suggest what is the recommended value for lock-wait-timeout option for innodba? Is it similar to InnoDB Lock wait timeout ?
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Export all MySQL users

I need export all of a MySQL database users (including permissions) for a migration. There is over 5,000 users, what is the best way to do this? Should I just dump the mysql.user table?
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Add user level permissions to MS Access by using a MySQL backend

I have a large Ms Access 2013 .accdb application which runs a lot of VBA code, with almost 60 users. I developed a user level permissions mechanism using vba but now plan to migrate the back-end to ...
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MySQL replication error: Table doesn't exist

I just run a MySQL database master-slave replication using these instructions. The process seemed to be ok, but when I run some queries on the slave server I get this message on 3 of my tables. ...