MySQL : Open-Source, Relational Database Management System

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Master-master Replication with 3 Nodes

I need to configure mysql master/master replication with 3 nodes. Currently I have master/slave setup and I need to move it to master/master with 3 nodes. I have gone through some posts about ...
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Is it possible to uninsall MySQL-5.6 and install MySQL-5.1 on RHEL 5

I have installed MySQL-5.6.x community edition on RHEL5. It was running fine. Since, it is my testing server. To find the differences in execution timing, I have to install the MySQL-5.1 community ...
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MySQL crashing randomly

We have a sever running a website Joomla 2.5. We are facing frequent mysql crashes that occur when website has medium visitor load like a few thousands. It appears that mysql consumes more memory and ...
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add column without metadata lock in mysql 5.6

I am using MySQL Server version: 5.6.15 Homebrew. I need to add new null column. alter table requires no metadata lock. In order to avoid this MySQL 5.6 introduced algorithm=inplace. Here is the ...
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Copy from one MySQL table to another MySQL table of same database

I have around 40 million rows in a MySQL table and I want to copy this table to another table in same database. What is the most efficient way of doing this? How much time will it take (approx.)?
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Pulling from Two Tables with Different Number of Records

I have three tables, one for members with 8 records, one for tasks with 1 record, and one for events with 3 records. The tasks table associates the events with members using one-to-many primary to ...
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Adding a constant IF not in an other table

So I have this query. SELECT * FROM `Comment` WHERE `Target` = '".$_GET['pp']."' AND `Id` NOT IN (SELECT `Target` FROM `Delete` WHERE `Type` = 'comment') ORDER ...
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query execution time in mysql

I have run the query in mysql which consists of approximately 33million records when i have executed the query select population1 < 200000 from city; it shows like this after execution ...
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Mysql Select using Alias

I Need to filter the query that have some conditional column as below: SELECT `c`.`fullname` AS `fullname`, IFNULL(`c`.`new_ic`,`c`.`old_ic`) AS `Ic`, `bla`.`loan_no` AS `Loan_No`, ...
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Merge a table into an existing one

I know how to JOIN two tables as create a new table out of the results, using CREATE TABLE result_table AS ( SELECT * FROM tableA JOIN tableB ). I forgot to include some columns from the JOIN in the ...
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Get travel_point.address_from and travel_point.address_to when driver_has_book.status is 0, 1 or 2

I'm building a view for get travel_point.address_from and travel_point.address_to when driver_has_book.status is 0, 1 or 2 (basically I'll need another data from related tables). I leave the SQL ...
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14 views

change character set in mysql permanently

I want to change following parameters to utf8mb4 so that mysql can store emoji characters and special language characters. but when i try running following statements one by one SET ...
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Find youtube url

Good afternoon, I need a help, through a select have to locate within a column all the urls from youtube 'https://www.youtube.com/watch?v=cod'* N codes, as necessary to generate a txt with these ...
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Bypassed, Empty Relay Log

We have a simple 1:1 Master-Slave replication configuration. The Master crashed, but we recovered and replication seems fine (confirmed by pt-heartbeat and SHOW SLAVE STATUS) but we've picked up one ...
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31 views

mysqldump --single-transaction, yet update queries are waiting for the backup

If I use mysqldump --single-transaction, according to the docs it should do flush tables with read lock to get a consistent state and then start a transaction and no writers should be waiting. ...
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MySQL getting killed by AppArmor

I have copied this link from StackOverflow as it is marked as out of topic there and is waiting to be transfered here. So, here it goes: Occasionally, without any identifiable pattern, MySQL ...
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21 views

Creating a registration page with PHP and PDO [migrated]

I need to create a registration page using PHP and PDO, and encrypt the password before storing it on the database table using md5 (adding 2 salts to the password). How can I write the script for ...
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28 views

call id of a table to a new table and insert values to this new table

I have recently started to write server scripts. Although the question may seem to be very basic but i am not able to get a solution. I have two tables one is PRODUCTS and the other is DEALS. ...
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32 views

Building a query programatically

I have three variables $color, $size and $category. Each oh them can be a specific value or may refer to all entries.I want to fetch all products that are $color = "red", $size = "Medium" and any ...
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A table that consists of multiple FK or creating separate tables for each FK

I have tables called 'books', 'category', 'subcategory', and 'booksCategory'. Each book can have its own category and subcategories. For example, a Sci-Fi book can belong in the 'category' table under ...
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26 views

Can I use mysql/mariadb databases on different OS?

If I will use mysql/mariadb on Windows and soon I'll decide to switch to Linux or vice versa, can I use databases created in one operating system in another one without any data-loss? Thanks in ...
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43 views

Inserting data into multiple tables

For my system, students are required to create a user account by completing a registration form (personal, contact and course details; also username and password). I need to collect registration data ...
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30 views

Sql statement to compare two table

I have two table with the same structure, i want an sql statement to compare them and see any modified line, deleted or added Table Product1 : ________________ |Product | Price| |Product1 | 10 | ...
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How to disable HTML output in mysql console?

I've used several mysql instances on many servers, but this one had a suprise for me tonight when I tried to use its console for the first time : me@MYSERVER:~$ mysql -H my_base (....) (...) Server ...
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Perform group by with random group expression (randomly partitioning rows) MYSQL

Let's say I have a table (with millions of rows) cat1|cat2|value A | B| 10 ... and I want to group the data by cat1 and also split the grouping into 10 (at least roughly) equal partitions of ...
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What subquery do I need to calculate this report?

I have two tables: tickets and comments. I need to run a report that shows me which ticket is "neglected" meaning that there has not been a comment in X amount of time. If I was to do this in PHP, I ...
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Building a dedicated physical MySQL server

I have a database that I use to mine a "primary" 20-column table with 18 million rows and growing by about 2 million a week, and that may accelerate. I am working to pre-process data by running PHP ...
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Perl - MySQL/MariaDB - slow with no identifiable bottleneck

I am running a Perl script (using DBI) which reads from raw files from a hard disk, and updates MySQL database (which is on a separate SSD). My performance is rather slow (1000 files processed in ...
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LDAP authentication with Percona Server

Reading over this post it seemed to indicate this plugin allowed user authentication via LDAP Percona Server is bundled with the PAM plugin which opens a plethora of ways to authenticate to ...
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32 views

Using a join to return multiple values of the same column?

I have two tables user Rank In the Rank table, I saved rank_id and supervisor_id. In the Rank table, I stored the rank name. The rank_id and supervisor_id are foreign keys from the Rank table. ...
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SQL SELECT - adding field to SELECT with JOIN is changing the results

I have a SQL sentence with JOIN, running on mysql 5.5.16: SELECT DISTINCT (ot.orders_id), ot.value FROM orders_status_history osh INNER JOIN orders_total ot ON ( osh.orders_id = ot.orders_id ) WHERE ...
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31 views

How to insert values into a table from two different tables?

I have three tables students table ------------------------------------ id(PK, A_I) | student_name | nationality teachers table ------------------------------------ id(PK, A_I) | teacher_name ...
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34 views

pass data from deleted table to another

This is the situation: I have a table, with name TABLE_1 I would like delete TABLE_1 and then create another table with the same name and some of its columns. TABLE_1 has records, but I need to pass ...
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29 views

Auto refreshing a query

I have a SQL statement update test_1 set `t_mark` = (`mark_1` + `mark_2` + `mark_3`) which works perfectly but I want the same statement to repeat automatically when a new row is added.
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Tools for migration from MySQL to PostgreSQL [on hold]

I have been trying with RazoSQL, mysql2pgsql and dbconvert. But none of this worked fine for me.
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MySQL 5.6: Slave_IO thread stops working

Standard replication breaks for no apparent reason. mysql> SELECT @@version, @@version_comment; +---------------+----------------------------------------------------------------------------+ | ...
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1answer
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Btree index and Bit Map Index [duplicate]

Please clarify the difference between BitMap Index and Btree index. I am using mysql version 5.5.37-0ubuntu0.12.04.1. I can able to create Btree index but unable to create the same, Please find the ...
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Inheritance discriminator column better int or varchar or enum?

What is the best practice for storing a discriminator column ? Does it make any difference ? Any pros/cons of using one over the other ? I am using MySql with Entity Framework but the question goes ...
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MySQL Cluster MaxNoOfConcurrentOperations and RAM

Why increasing of MaxNoOfConcurrentOperations lead to higher consumption of RAM? I need high value for fast filling tables with some random data, but i noticed that my datanodes are swapping at ...
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ON creating BITMAP INDEX on a table in mysql throws error

say, i have database named "demo_dev" database and added a table named "countries". i wanted to create bitmap index on a column say region as it has less unique values using following query. CREATE ...
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Mysql checksum for master-slave replication returning different values, despite being identical

I've set up a master slave replication in mysql and to make sure that I know if the data starts getting out of sync I created a script that: Locks both databases on both servers. Prints the ...
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how to view the Image in mysql DB

Hi How to retrieve the image in mysql I had created a table employee_details CREATE TABLE `employee_details` ( `emp_id` int(50) NOT NULL, `emp_name` varchar(50) NOT NULL, `dept` varchar(50) ...
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How to connect to remote MySQL server with sshuser and mysqluser being distinct

I'm trying to connect to a remote MySQL server via ssh so that I have write-access to export some data. At the moment I can do the following: Connect to the remote MySQL using mysql -u mysqluser ...
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Get only the oldest entry in a join

So I have a table bugs |bugid| title| the table is lacking a date column. But when creating a new entry, most likely always a new entry gets created in bugnotes as well saying "bug created" with the ...
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MySQL WRITE LOCK Not Preventing Inserts

This should be a simple task. Can someone tell me why the below code is still inserting rows? lock table wp_postmeta write; insert into wp_postmeta values (null, 1,'test','test'); I've checked my ...
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29 views

Load csv into MySQL database programmatically

I know about LOAD DATA INFILE command -- however, this requires that we already have the table with appropriate columns in place. When I have csv with hundreds of columns, it is not feasible to type ...
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How to optimized mysql query having large dataset

I have two tables in MySql with the following schema, CREATE TABLE `open_log` ( `delivery_id` varchar(30) DEFAULT NULL, `email_id` varchar(50) DEFAULT NULL, `email_activity` varchar(30) DEFAULT ...
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How to simulate a table join on itself?

Let's assume this is my current data: product_number date value 100 2010-01-01 1 100 2010-02-01 1 100 2010-03-01 1 200 2010-01-01 1 ...
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Select the last logged change before a specified time from a change list

I want to get the last change for all issues issue, that was made before a specified end time. I have 3 tables. projects +---+------------+ |ID |project_key | +---+------------+ |1 |bug_tracker | ...
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MySQL Cluster ndb_desc and parttions

I have mysql cluster with two datanodes and noofreplicas=2. According to documentation there must be 1 nodegroup, 2 partitions and 4 parts at all (2 primary and 2 backup). I have a table with 1000000 ...