MySQL : Open-Source, Relational Database Management System

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3
votes
2answers
712 views

Sorting the Table and getting the position

I am able to sort a table using the following code:SELECT * FROM Persons ORDER BY LastName But I wanted to get the ranking/position of a person using that order. For example when I sort Person table ...
5
votes
1answer
1k views

Mysql sub query returns more than 1 row

SELECT * FROM wp_posts WHERE ID IN ( (SELECT courses FROM wp_category WHERE CatID =401) OR (SELECT meta_value FROM wp_postmeta WHERE post_id IN (SELECT courses FROM wp_category WHERE CatID =401) ...
7
votes
2answers
1k views

MySQL : perform a big data migration between tables

I want to migrate data between 2 InnoDB tables. Currently I'm running this query: INSERT INTO table_a SELECT * FROM table_b; If the dataset grows, what's the best way to avoid CPU overload? ...
0
votes
2answers
3k views

Oracle database link to MySQL database on RedHat Linux

I have an Oracle 11g database on a RedHat server and also have MySQL database on another RedHat server. I want to create a link to the MySQL server from the Oracle which allows me to execute queries ...
0
votes
2answers
95 views

MySQL still holding memory after I shut it down?

I used this command to shutdown MySQL, however it seems the amount of free memory on my box has not changed? That seems to odd. /usr/local/webserver/mysql/bin/mysqladmin -u ${mysql_username} ...
10
votes
3answers
1k views

Where is the INNODB Performance Leak?

I have a weird problem which I cannot seem to fix. I'm more an web programmer than a Server/DB Admin, so I hope someone here can help me. The Situation I am working on a system which handles a lot ...
0
votes
1answer
261 views

What would be possible reasons for a DeadLock to occur in Mysql Database?

If some one has a Table structure some thing like this, CREATE TABLE IF NOT EXISTS `domain_source` (`nid` int(11) NOT NULL DEFAULT '0', `domain_id` int(11) NOT NULL DEFAULT '0', PRIMARY KEY (`nid`) ) ...
1
vote
2answers
851 views

SQL Partioning on date, how does it work for future records?

I am setting up a new system and I would like to partition the data for speed. Basically what I would like to do is have one database with all the latest information (e.g. last 3 months). then have ...
2
votes
1answer
894 views

MySQL query not using an index when table contains many records

I have a table: CREATE TABLE `p` ( `id` BIGINT(20) unsigned NOT NULL, `rtime` DATETIME NOT NULL, `d` INT(10) NOT NULL, `n` INT(10) NOT NULL, PRIMARY KEY ...
2
votes
1answer
865 views

MySQL: AVG of defined variable per month

I need help with the following code: SELECT DISTINCT userid , count( userid ) as login_count FROM ( SELECT DISTINCT userid , ...
4
votes
1answer
896 views

MySQL Import CSV with Multiple Field Separators

I'm trying to import this CSV file into MySQL that appears to be optionally enclosed by more than one character. Unfortunately, MySQL only supports one character as a field separator. I am stuck ...
4
votes
1answer
569 views

MySQL: Delete a record from all tables in one shot

I have a MySQL database, with one table that has a primary key, f_id that is referenced in multiple table as a foreign key. I want to delete all records where f_id is a specific value from all ...
4
votes
2answers
324 views

How to speed up this simple mysql query?

The query is simple: SELECT TB.ID, TB.Latitude, TB.Longitude, ...
7
votes
3answers
6k views

How to Best Implement nearest neighbour search in mysql?

So, in short, What should be the data type of latitude and longitude? What SQL command I should call to get the first 100 nearest restaurants for example? Detail: I have 100k biz record each with ...
2
votes
1answer
91 views

Count total where owner_user_id = some_value and deleted_by_owner = 0 or to_user_id = some_value and deleted_by_to = 0

I didn't know if this is possible using just a query or if I need some procedural logic on this one. I have this table: CREATE TABLE `default_messages_users` ( `id` int(11) NOT NULL ...
3
votes
1answer
1k views

Getting duplicate primary key for auto increment coloumn

I have a MySQL Innodb table with 'id' as auto increment primary key coloumn. My Scripts are doing following operations: insert ignore into tablename set x='a', y='b' update ignore tablename set ...
1
vote
1answer
949 views

How should I update ID field values for all records based on previous values?

I need a SQL query that can update ID fields for all records in a table from their previous values to a new value based on that previous value. For example, if the ID is 1, I want to change it to ...
1
vote
1answer
278 views

MySQL suddenly running very very slowly

I run a PHP/MySQL website on a fairly large server with 16GB RAM and 3 vCPUs. Everything was flying along until this morning when I noticed MySQL down. I tried to restart MySQL and first got the ...
2
votes
1answer
3k views

How can I limit MySQL connections?

Last week, our MySQL database got overwhelmed with a lot of connections doing INSERT / SELECT queries. I have talked to the developers who say it will take weeks to fix this issue. In the mean ...
5
votes
1answer
2k views

MySQL dump restore - how to retain comments

So I have that complex MySQL dump as a backup. Unfortunately, that backup is complex and we use evil triggers. Some of our evil triggers had a comment lines starting with the # character. When I ...
3
votes
4answers
5k views

Is MySql locking table during backup and how to avoid?

I have a scheduled backup that runs daily in MySQL and I have noticed that during the backup a lot of queries that query a frequently used table seem to take forever to complete. This causes the ...
2
votes
1answer
226 views

MySQL : Does 'bytes_sent' and 'bytes_received' include mysqldump data?

I'm trying to estimate my db traffic not including backups (mysql 5.1.41). I use show global status; to get the parameters bytes_sent and bytes_received. Questions Do these numbers include ...
2
votes
3answers
2k views

How to detect a running mysqldump?

Here are the things I can't change: We got a mySQL myISAM replication running a master and some slaves. One slave is being used for nightly backups using mysqldump. The backups is using heavy locks ...
1
vote
2answers
422 views

Managing features for a real estate agency [duplicate]

I have a database table real_estate where the basic information is held (id, status, sku, address, building_type, sales_status) and now I want to attach features to that real_estate table. The data ...
0
votes
1answer
542 views

MySQL table with multiple values in one field

I'm building a database for a real estate company. The real estate properties are managed by sales people using a CodeIgniter website. How should I proceed with the database design for this table? ...
-1
votes
1answer
512 views

Very slow MySQL query. Index problem?

I have a query like this: SELECT BE.NAME as NAME, BE.PREVIEW_TEXT as PREVIEW_TEXT, BE.ID as ID, FPV1.VALUE as PROPERTY_COUNTRY_VALUE, FPV1.ID as PROPERTY_COUNTRY_VALUE_ID, ...
1
vote
1answer
4k views

Connecting remote MySQL database to local MySQL database?

I want to write PHP code to be embedded in a Drupal7 module. I want to call a procedure which can copy newly generated data in the local MySQL database to a remote MySQL database. When data is ...
2
votes
2answers
4k views

Remove the last character from Variable String

I have a few variable data in the column "email". For example: roy2087@gmail.com123 sg123@yahoo.compori How do I get rid of the characters after .com? I used Replace(email,'.com%',gmail.com), ...
1
vote
2answers
101 views

Basic PARTITION question in MySQL

Say I have an application using MySQL and at some point decide that implementing Partitions on certain tables might improve performance. Would I need to change the applications select statements ...
2
votes
1answer
571 views

InnoDB not enabled

I have a mysql database that when I run SHOW ENGINES; innodb does not show up as an engine. This seems strange as I have an identical server setup where innodb is enabled and in use. I have checked ...
2
votes
1answer
641 views

MySQL wont start after modifying /etc/my.cnf

I have Linux Red Hat 5, with Zend Server and MySQL Server installed. I am trying to change the default MySQL port to 512. However, after making this change, MySQL will no longer startup. I get the ...
1
vote
1answer
394 views

MySQL to add to cart 1-4 Socket Server

When I check for price tags for MySQL, I see a clause called "1-4 socket server" or "5+ Socket Server".. what does this mean? "Socket" in generic term means Inter Communication Protocol. For MySQL, ...
3
votes
2answers
7k views

Why is my MySQL dump file and my phpMyadmin export file different sizes?

I am looking to create a cron job to backup my MySQL database. I am using this command: $ mysqldump --user="User" --password="Password" -A --single-transaction > /home/user/Export-`date ...
4
votes
1answer
103 views

Is it possible to encapsulate a table in MySQL?

I am new to Databases. I want the following: UPDATEs in a database to happen only through a stored procedure The user does not have GRANT UPDATE The user has GRANT EXECUTE ON PROCEDURE I tried it ...
4
votes
2answers
7k views

How do I get the current and next greater value in one select?

I have a InnoDB table 'idtimes' (MySQL 5.0.22-log) with columns `id` int(11) NOT NULL, `time` int(20) NOT NULL, [...] with a compound unique key UNIQUE KEY `id_time` (`id`,`time`) so there can ...
3
votes
1answer
1k views

Does the Amazon RDS backup/snapshot service lock tables?

We have a database that is 100+GB. Most tables use the InnoDB engine. A regular dump takes 1-2 hours. If we moved to Amazon RDS, would this backup cause table locks? Does Amazon use a simple ...
4
votes
2answers
2k views

What is the best identifier for a UserID? 64 bit integers, UUID V5, or 64 character SHA256 UID?

I wish to future-proof my application. What is the best type of identifier to use? I am considering: 64 bit Integer UUID 64 character SHA256 I am not developing a distributed system, so is ...
5
votes
1answer
268 views

Prevent users deleting more than a certain number of rows in MySQL

The problem: I have a table with rows, nothing special about it When a database user removes a row, it should increment a number A database user is only allowed to remove 3 rows max in the table A ...
7
votes
1answer
859 views

Friends relations in MySQL

I'm developing a friendship relation in MySQL where friend relation is mutual. If A is friend of B, then B is friend of A. If one of the users end friendship then relation drops. I want to learn which ...
2
votes
2answers
963 views

How do I import a specific line from a text file into MySQL

I'm building an app to import data from a text file to a database. I want to import only specific lines from the text file. With Navicat I found that we could limit number of line when importing ...
10
votes
1answer
6k views

Clarification on MySQL innodb_flush_method variable

Let me begin by admitting that I'm very ignorant of the inner workings of hard disks. So when I read over the manual for the variable innodb_flush_method, it confused me. Can I get an explanation in ...
0
votes
2answers
2k views

MySQL replication fails due to duplicate keys after master is restarted

I'm new to MySQL load balancing, I want to try the master-slave concept. Whenever I setup master-slave for the first time, and both have up-to-date fresh data, that works perfectly fine. However, ...
0
votes
1answer
2k views

Db design for a quiz with variable number of answer choices, and each worth different score in a different category?

I'm working on a question/answer project and having a hard time coming up with a suitable database structure. Each question can have from 1 - "n" answers, and each answer is associated with one of ...
2
votes
0answers
7k views

Alternative OpenSource/free to MySQL Cluster Manager Client? [closed]

I need to deploy a MySQL cluster but initially no bucks for the MySQL Cluster Manager Client. It's at least $5k and I actually think in my case it will go way over that. I looked a lot on Google (a ...
3
votes
3answers
3k views

MySQL: selecting arbitrarily ordered rows after a specific id

Please excuse the awkward wording of my title, I'm not quite sure how to phrase what I'm asking. Suppose I have a table like this: id value 1 10 2 40 3 20 4 50 5 40 Running this query: ...
1
vote
1answer
814 views

MySQL Cluster over WAN: Best Architecture Options?

My company is looking at a multi-data-centre solution for high-availability, fun, and profit. We have businesses across the planet, with the need for MySQL database clustering solutions that can keep ...
2
votes
3answers
142 views

MySQL operations on grouped fields

I have one table t1 like this a|b|c -|-|- 1|1|2 1|1|3 1|1|6 1|2|3 1|2|4 1|2|7 1|3|5 2|3|2 I would like a query where the results would be similar to running multiple selects like this: (SELECT * ...
2
votes
1answer
532 views

Should I use left join to do my job in this scenario?

What I want to do is to find out the items which appeared more than once in this table: mysql> desc tables; +-----------------+---------------------+------+-----+---------+-------+ | Field ...
4
votes
2answers
1k views

Is my EER Diagram correct? Why use relationships?

This is the first time I've made an Entity Relationship Diagram (ERD) for MySQL. Prior to this, I would never create relationships between tables, I would simply create the tables in MySQLAdmin and ...
4
votes
1answer
1k views

How can I prevent gaps in a MySQL table AUTO_INCREMENT field?

For example, I have a table for user registration: CREATE TABLE IF NOT EXISTS test_user ( user_id int(10) unsigned NOT NULL AUTO_INCREMENT, user_name varchar(50) NOT NULL, PRIMARY KEY ...