All versions of MySQL (not Microsoft SQL Server). Please also add a version-specific tag like mysql-5.7 if that is relevant to the question.

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-1
votes
1answer
159 views

Show all categories from CATEGORIES table [closed]

I have these two tables, categories and files And I have this query that shows only one result/row. SELECT `categories`.`category_id`, `categories`.`timestamp`,`categories`.`name`, ...
0
votes
1answer
166 views

is this database structure correct?

I need some help with a new database structure because I want to make it right. Later in the app you should be able to create users, events and groups. When you create a group you can add members ...
0
votes
1answer
52 views

MySQL: Algebra in Union operation

I have below query: select entity_id from table1 exc UNION select entity_id from tabl2 inc On execution, I got 24419 rows. When I execute select entity_id from table1 exc I got 16235 rows and on ...
1
vote
2answers
249 views

Create read only user without being root

I want to create read only user in MySQL without any intervention of root user. CREATE USER ‘$user‘@’127.0.0.1′ IDENTIFIED BY ‘$password‘; Works for me only If I am a root user. But I want it to ...
3
votes
4answers
503 views

How to design a table that each rows have 5K boolean attributes?

I have about 2M rows and each row looks like the following. 244 true false ... true -> One integer column(V) and about 5K boolean columns(B1, B2, ..., B5K) associated to the integer. Due to the ...
0
votes
1answer
1k views

Getting an error in MySQL Workbench: Cannot Open Administrator

I'm using local installation of MySQL CE on Windows 7 64-bit. Tried to use Administrator part for the first time. Here's the error I'm getting: I also see the following in the log: <object ...
0
votes
2answers
1k views

Read massive flat file into relational database

I have a massive flat text file with ~4M records that I would like to read into MySQL using Ruby/Rails, Python, or any other method. The flat file is roughly this format: ...
3
votes
3answers
4k views

Cannot write to mysql database while select query in process

Running Mysql 5.1.57 on InnoDB, and have a database locking issue. I have two separate sessions connected to a single database MySQL. On the first session, I run a long SELECT query (technically a ...
2
votes
2answers
146 views

My query fails to segment the results as intended. What am I doing wrong?

Update: Re-phrasing the question. Below are the results and the desired results. What do I need to do to get the desired results? See http://sqlfiddle.com/#!2/d0e13c/69 Thank you SELECT ...
0
votes
1answer
661 views

how many 'text' column a table could have in mysql? I have this error “Row size too large (> 8126).”

I'm working on a application which is kinda complex to explain how it works. But this is the situation I'm in, ------------------------------------------------------------------------------ FIELD1 ...
0
votes
1answer
234 views

Why is setting open_files_limit making MySQL slow?

We noticed that adding open_files_limit in /etc/my.cnf is making server slow. Reference : What variable(s) to look to maintain MySQL speed of scanning through all database tables while it starts?
-1
votes
4answers
13k views

Host is not allowed to connect to MySQL

I have already uploaded some files in the free web host I chose and created a database there using phpMyAdmin v2.11.4 Also, I have Googled first this question before posting this here but I don't ...
0
votes
2answers
4k views

Saving every mysql user login attempts

Is there a way to save the username and the IP from which the user tries to login to a MySQL server?? Enabling general-log seems to log everything but that seems to write too much details taking more ...
2
votes
2answers
7k views

MySQL Workbench connect to MS Access

I have a .mdb file on my computer that I would like to convert into a MySQL Schema and I have found that there is a migration tool within Workbench. However it doesn't seem to allow you to connect to ...
1
vote
1answer
292 views

How to get the last inserted id using scope identity without using a stored procedure in Mysql?

My project contains 2 tables one is profile_table and another is address_table Profile_ table contains: +------+---------+----------+ | sid | sname | saddress | +------+---------+----------+ | ...
1
vote
1answer
71 views

How to read queries of master that sends to slaves?

I want to see queries that Master sends to slaves in Mysql ? Is there a way to see that ?
2
votes
2answers
977 views

Amazon rds MySql -> concurrent connections deadlocks

I normally hang around in StackOverflow but I think this issue is better suited here. I've built an application in C#.NET that uses MySql as a database. My application inserts and updates data in the ...
0
votes
0answers
215 views

Database normalization tables

I am creating a database for a very basic website. I have created the tables and put what I thought might be the correct schema, however I am having doubts about it as well as a couple problems. All ...
1
vote
0answers
38 views

Host is not allowed to connect to MySQL [duplicate]

First of all I'm acknowledging you that I am a completely newbie in this field. The field I'm referring to is the summation of these things: Accessing files on different computers or over the ...
0
votes
1answer
95 views

Is it OK to duplicate parent field in child table for performance?

I have a very complicated query which involve more than 10 tables. Some parent tables are loaded only to search on one field. I wonder if I can copy this field in the child table (this data is never ...
2
votes
1answer
65 views

InnoDB buffer pool active pages

I'd like to optimize (lower) the InnoDB buffer pool size. How can one find out how many distinct pages are active in the InnoDB buffer pool? A page could be made young twice in a while (see SHOW ...
8
votes
2answers
430 views

Why would MySQL do serial synchronous I/O?

When looking at a particularly annoying query over MyISAM tables which takes a long time to execute on a number of occasions, I have noted that MySQL seems to expose a rather strange I/O pattern: when ...
3
votes
1answer
6k views

Use limit with where clause in in mysql [closed]

I know where clause search and display the records as per criteria comes true, and limit is use to fetch the number of records from a table. But please help me when I am trying to use them both ...
0
votes
0answers
91 views

Sorting the view on which the stored procedure runs

I want to sort the view on a particular column before my stored procedure runs. Is there a way to do this through the stored procedure? Can anyone show me a MySQL example? This is what the stored ...
1
vote
1answer
1k views

MySQL select query result set changes based on column order

I have a drupal 7 site using the Views module to back-end site content search results. The same query with the same dataset returns different results from MySQL 5.5.28 to MySQL 5.6.14. The results ...
1
vote
1answer
988 views

Design for active/passive Master-Master mysql Setup

I have a dozen virtual machines running application + mysql instances (version 5.1 up to 5.5). Due to the bad I/O of the virtualization I want to buy a physical server for mysql and move all mysqldata ...
1
vote
0answers
9k views

MySQL server taking up 100% CPU

I'm managing a site that does streaming video, the site is running off: Intel(R) Xeon(R) CPU E31220 @ 3.10GHz 16 GB RAM 2 x 2TB RAID1 1gbit unmetered bandwidth is not an issue as the ...
10
votes
6answers
4k views

What could be causing strange query timeouts between PHP and MySQL?

I am the senior developer on a Software-as-a-Service application used by many different customers. Our software runs on a cluster of Apache / PHP application servers, powered by a MySQL backend. On ...
0
votes
1answer
76 views

Last used index from specific table

how can i take last used index from a specific table and add a +1 to it? database login, table cars I think i need to add it here #### $sql = 'INSERT INTO '.$this->options['db_table'] ...
2
votes
1answer
282 views

Do triggers affect DB performance

I have a database with 250 small and medium sized tables. These tables are related with both MyISAM and InnoDB storage engines. There are multiple triggers that have been created on different tables. ...
0
votes
1answer
579 views

UPDATE CONCAT without duplicates

I would like to concatenate multiple values ​​and remove duplicates (case-insensitive) in the same field with SQL only. Without using a unique key or stored procedure. Ex. ...
1
vote
2answers
253 views

Why does “SELECT *” take longer than “SELECT <primary_key>”?

I'm having a problem with a query running on a little PHP program. When I use * to select all the columns, it takes way more to return the result than when I use just one column. The query that is ...
3
votes
1answer
482 views

MySQL Replication : Duplicate entries - SQL_SLAVE_SKIP_COUNTER or delete row?

I have a system which replicates one database to four slave servers. Every now and then, when traffic is high, one or more of the slave servers hits a duplicate insert error and the slave stops ...
2
votes
0answers
630 views

Recover innodb database from ibdata1 and *.frm files only

I have a problem on my server. I had a hard disk error on my server, and I restarted it. After that, I started wamp server software, but mysql services were not started. I checked all mysql data, ...
2
votes
2answers
127 views

General structure advice for beginner

I am starting my first DB-Driven website project for a mock real estate agency and would like a bit of feedback on my general approach to how I will drive the site with the DB. Specifically I'm ...
1
vote
1answer
571 views

Optimizing a large number of INSERT … SELECT statements

I have a MySQL InnoDB database with two tables related by a foreign key. Each time a row is inserted into one it uses an INSERT ... SELECT statement from the other to get the corresponding foreign ...
1
vote
1answer
163 views

MySQL Enums have non-intuitive behaviour, why?

This very helpful article explains some oddities about how MySQL Enums behave: http://melp.nl/2009/05/mysql-enums-and-booleans/ There is no discussiong about why that behaviour exists. Furthermore, ...
0
votes
0answers
39 views

Trying to import an addressbook

I'm trying to import a .sql-file that I got by converting an .dbf-file. The problem is this line: INSERT INTO address values ('', '', 'Dekanat', '', 'Fachhochschule Hildesheim/Holzminden/Göttingen', ...
0
votes
0answers
228 views

Latest of group in subquery is bottleneck, how to optimizing query?

See Original question I'm fetching the activity data for the latest activity for each company as part of a bigger query. I've been using the method provided by ypercube, and it works fine, but I find ...
0
votes
0answers
61 views

Is it possible to group by a fraction of the result set?

I have a database of products with prices. What I'd like to be able to do is figure out 5 different price ranges such that each range, when ordered by price, will have approximately the same number of ...
2
votes
2answers
604 views

MySQL 5.6 showing wrong “second_behind_master”

mysql> show slave status\G *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 10.10.7.98 ...
4
votes
1answer
591 views

MySQL - GROUP_CONCAT returns duplicate data, can't use DISTINCT

I have a normalized database and I'm trying to return data from multiple tables using JOINs and GROUP_CONCAT. Problem: Rows are being duplicated with GROUP_CONCAT. I can't use DISTINCT because some ...
0
votes
1answer
13k views

MySQL: split value in column to get multiple rows

I have some data in a table like so: product_id categories 10 9,12 11 8 12 11,18,5 I want a select statement that would produce this output: product_id ...
3
votes
1answer
4k views

What is better in IN()? Sub-query or list of values

If search or update rows and use where statement IN() - is better to select values with sub-query or define values or there is no efficiency difference between this? For example: SELECT a FROM b ...
4
votes
1answer
15k views

Get a fixed value on a select

I need to do a SELECT query where I get the value of the field "money". The field doesn't actually exist in the database. I just need the query to return this field with a fixed value; in this case ...
3
votes
2answers
2k views

Grant access to a table to all users

Is it possible to assign a grant to a table for all users, or a default permission so that when new users are created they will have the specific grants for that table to SELECT, UPDATE, INSERT and ...
3
votes
2answers
239 views

Is it suitable innodb_buffer_pool_size for MySQL Master-Slave

I am wondering how to decide the value of innodb_buffer_pool_size for my Master-Slave style database. I have a set of MySQL, 1 x master + 1 x slave. As I know that the innodb_buffer_pool_size is ...
2
votes
1answer
81 views

Start and Stop entires in MYSQL Logs

I am a newbie to MYSQL and I am trying to check where does MYSQL log start and stop entry with timings. I have issue in my application where I get communication link failure at random intervals and ...
0
votes
1answer
557 views

How should I config the my.ini(or my.cnf) file for mysql?

Thanks for taking your time to look at my question, and I hope that you can help me with this. I have a Windows Server 2012 server, it has: Memory : 3840MB Ram Processor: Intel(R) Xeon(R) CPU ...
0
votes
1answer
900 views

MySQL will not start

Please help, I really need to recover my databases. service mysql start start: Job failed to start mysqld --verbose 140401 20:16:11 [Warning] Can't create test file ...