MySQL : Open-Source, Relational Database Management System

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MySQL - Where can I find metrics on the performance of Blob vs file system?

I know and understand that there are performance hits in storing blob data in the database, but the blob portion of the data is going to be rarely retrieved/viewed, it is for smaller data (the vast ...
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Can MySQL walk through the files of a directory?

Like the title says: can MySQL (alone, i.e. without C or Python) walk through the files of a directory? Or can you only do this through an API? Sorry for the dumb question. Total noob here and I ...
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Grouping Data Using Joined Tables with Certain Distinct Values

I am struggling to get my head around how to do this so please bare with me while I explain. We have an order system which records orders, order lines, items, users etc. What I am interested in in ...
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35 views

Optimizing Queries HAVING COUNT and INSERT…ON DUPLICATE KEY UPDATE

There are two main queries I'm tying to improve, one question is much more conceptual and learning about databases and another is much more straightforward. Both cases deal with the same table It has ...
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16 views

SET sql_log_bin = 0 in RDS MYSQL 5.6

I have moved into RDS MYSQL 5.6. Now, I have a problem. I have 5 read replicas and a/z master. I am trying to perform an ALTER TABLE and want to change a column value and also on some tables I want ...
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28 views

Why do the queries slow down after a few minutes, when trying to build a DB?

First - I am a complete newb to DBA. Please be gentle. (And I am fairly new to python as well.) Oh, and I have no idea how to change any MySQL settings or the like, so all the MySQL DB settings are ...
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42 views

MYSQL View with LEFT JOIN return all possible combinations

I am working on a view that joins multiple table. The data will be entered on separate table based on RepairID. The view will gather the data that is linking to the RepairID. My problem is after I ...
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1answer
30 views

Database Dump/Backup but only to specific records?

This question is about MySQL Backup (or Dump) whereby i want to backup and store information from only information related to a person; SchoolA from the School Table in this example. So, I should not ...
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20 views

Have several rows, or one single row with a huge comma separated data?

I have many workers processes working at the same time. They grab an ID from a list called available_ids, work on that ID, and put that ID on a list, called used_ids. The list available_ids can have ...
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How can I allow a user to query a view but not the underlying table in MySQL?

I have searched for this question but cannot find an answer. Or, the answers I have found have been related to SQL Server. This is for MySQL 5.x. Anyway, say I have a table called Employees and in ...
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How to structure different types of a model in MySQL?

I am building an application where users can apply for small business loans. There are 4 types of loans (A,B,C,D). There are 10 commons questions no matter which type they choose, but then based on ...
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Mysql replication to empty db

I had a db master/slave setup that had hardware break on the slave. Now the server is backup I reinstalled mysql and setup replication the issue being backups are off. Is there a way to start mysql ...
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16 views

Can't create file /var/lib/mysql/user.lower-test

MySQL database has been problem free for a few months. Today when I checked for upgradeable packages using the Synaptic Package Manager it came up with the various MySQL components (-common, -client, ...
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15 views

Tuning Issue / Temporary Tables

I've got a MySQL database (MyISAM) that handles a lot of read/writes and uses temporary tables quite frequently. Recently it's started having massive load spikes at peak load, and noticed that there ...
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2answers
51 views

SQL - Select Rows in a Certain Order

I'm new here - if I missed anything in the question please let me know. I'm trying to build a people directory like LinkedIn has: http://www.linkedin.com/directory/people-a I don't want to fetch ...
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1answer
31 views

MySQL: not quoting WHERE conditions slows query execution

I just ran into a curious issue with MySQL. I had a very slow query, even if properly indexed, which was like this: SELECT * FROM `tbl1` WHERE `parm1` = 'taleggio' AND `parm2` = 10 As said both ...
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33 views

Where to place a foreign key column?

This isn't exactly related to modeling the database but rather about "standardizing" column placement. Where should I generally put my FK column? As the last column of the table? At the start just ...
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1answer
23 views

Need some assistance on MySQL Sub query

I have a table in MySQL. The table structure is as follows. id | emp_id | call_start | call_end | call_type -------------------------------------------------------- 1 | 20043 | ...
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1answer
25 views

MYSQL crashes on XAMPP while working with drupal

Good day, just today morning i was using drupal to add some content, it crashed and mysql shutdown unexpectedly at xampp!! last thing i was doing was inserting a data into a field with "auto complete ...
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1answer
21 views

Weed out certain rows where timestamp is within interval

Given a table structure: create table contacts ( contact_id int(8) not null auto increment, #primary key pid int(8) not null, #personal id contakt_time datetime, ...
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1answer
16 views

MySql Lock Tables Blocking Logic

The MySQL documentation (5.5) for Lock tables states: Let's say that I'm trying to lock table1 and table2 in a single query, but table2 is already locked. Will MySQL hold onto a lock on table1 and ...
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1answer
32 views

MySQL Filesort/Order By Slow

I've been struggling with a query for the past few weeks and it now just appears as gobbly-gook to me when I try to optimize. The query runs - at about 2.3 seconds, but I know there has to be a more ...
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28 views

sql join with laravel query builder

I have a transactions table with the following field: Transactions ID | amount | branch_id | supplier_id 1 | 1,200 | 2 | 1 Subsidiary ID | Name | Type 1 | supplier1 | 0 2 | ...
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24 views

MariaDB 10 InnoDB Partition with Data Directory

mysql --version mysql Ver 15.1 Distrib 10.0.20-MariaDB, for Linux (x86_64) using readline 5.1 I have a MariaDB 10 installed, though I tried with the 5.5 release in the CentOS repos. I'm ...
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95 views

Are junction tables a good practice?

Say I have a large table that holds the user's info and another table that holds several locations. Then I use another table that holds the user_id and the location_id. In order to retrieve the data ...
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Optimization of stored procedure MySQL [on hold]

I have a stored Procedure comparing two tables. This uses Cursor comparison logic , Source and the target cursors are used to compare two tables and find out the differences in tuples . This ...
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49 views

Fulltext search using multiple indexes

I have a table with several columns, say a, b, c, d that should be searchable. The problem arises when I need to search a, b, c separately from d (and vise-versa). AFAIK, there's no way to achieve ...
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Complicated MySQL table reorder

I should do really complicated tables reorder. ****The main table looks like:**** id - some data 1 - ... 2 - ... 3 - ... 6 - ... 9 - ... 12 - ... As you can see, there are "empty" IDs (no 4, 5 ...
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31 views

How to use a MySQL error handler in a stored procedure with prepare/execute

I have a procedure defined like this: drop procedure if exists drop_tables_like; delimiter $$ create procedure drop_tables_like(myint int, pattern varchar(255), db varchar(255) ) begin DECLARE ...
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1answer
51 views

Missing DB entries

I have run into a problematic situation. I oversee the administration of 5 php web pages on one server, each having their own database. All pages work like interactive forms drawing and storing data ...
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8 views

a phpMyAdmon database question [on hold]

I have two tables in database of phpMyadmin. One table is symptoms table, and 2nd is diseases table. The symptoms table has two columns: smpid and symptom The diseases table have three columns: ...
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1answer
24 views

I created a DB schema for a project relating to collecting comments for web pages, is relational the way to go and how are my relationships?

I'm curious if relational DB is the way to go, if the current relationships in the diagram make sense, and whether it will bode well for coding.
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MySQL: Using DATE_SUB to subtract business days instead of all calendar days

I am looking for a robust solution to subtract the number of business days from a date. I am using DATE_SUB however it subtracts all calendar days. For example, if today is Monday and I subtract 2 ...
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26 views

Help with PHP code, SELECT from database [migrated]

<?php session_start(); include ('connection.php');?> <?php $username='pablorex192'; $consulta=mysql_query("SELECT question FROM users WHERE user = $username") or die ('This is the error: ...
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2answers
46 views

Modeling invoices and orders

I have a problem in modeling a database that contains orders and invoices. Actually it's more of a problem from a business point of view, but it's related to modeling the database nonetheless. Model ...
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1answer
33 views

Modeling discounts - Product specific and Customer specific discounts

I have a reasonably simple database but have the following problem: I'm modeling a store + a lot of non-relevant stuff database. I have the following problem. I want to allow for specific products to ...
3
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1answer
18 views

automatically change value on the table mysql

i have table invoice in my database that contain atributes 'due date', 'date' and 'status'. What i want is data on 'status' change automatically. Example, status (unpaid change to expired) when date ...
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2answers
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Any ideas on how to parallelize mysql_upgrade?

I am migrating from 5.5 to 5.6 and would like to speed up the mysql_upgrade process. I have thousands of databases per machine and 200 tables (innodb) per db. Any suggestion how to speed up the ...
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0answers
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Mysql high cpu usage - cpanel

After an update from whm, I see a high CPU usage from MySQL (5.6). my.cfg: [mysqld] slow_query_log=1 slow_query_log_file="/var/lib/mysql/slow-query.log" long_query_time=1 skip_name_resolve ...
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Mysql user accesable with out password from the host machine but not from the remote machine

I have setup mysql and created a user 'test' and have given a password for it. Strange thing I observed is, for test user I am able to access with out password from the machine I have installed mysql ...
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1answer
27 views

Is there any difference between 'LIMIT 0, 1' and 'LIMIT 1'?

I recently stumbled upon example codes, which differed by these notations. SELECT * FROM table LIMIT 0, 1 SELECT * FROM table LIMIT 1 The first argument should be considered as the offset if I'm ...
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nbsp character might not be passing as nbsp to the MySQL backend

I am following a tutorial where a web application written in PHP, blacklists spaces from the input(The 'id' parameter). The task is to add other characters, which essentially bypasses this blacklist, ...
2
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1answer
89 views

Does PostgreSQL support online schema modification (DDL)?

Recent versions of MySQL (using InnoDB) support many alter table queries without exclusive locking the table. Does PostgreSQL support this to any level? That is, can I add/drop columns from a table ...
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performance of dml statements in mysql [on hold]

how can we increase the performance of insert and update statements in mysql procedure. and also if a procedure has only updates statements Blockquote ...
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1answer
21 views

Database design, many rows or many columns?

I am aware that this has been discussed before, but I've read conflicting information about this particular topic, so I'm hoping for a bit more decisive opinions from you. I have multiple tables, ...
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1answer
40 views

Update records from one table to another in different databases where condition is accomplish

I have two tables stored in two differents DBs and I need to perform some sync between both tables based on lastmodifieddate and lastSyncAt. Let's call them as db1 and db2. This is the DDL schema for ...
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1answer
35 views

Migrating Oracle 9i database to MySql database on a different Windows Server

I need to migrate my Oracle 9i database with all its tables from windows server 2003 to MySql on another Windows Server 2012. The oracle database is connected to Visual Studio web project. I have ...
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How can I retrieve the column names of a table in mysql?

I have a table with n columns. I want to retrieve the first 3 column names of that table. Should be something like this: Select column_name(3) from table_name="sample";
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69 views

Configuration required for a big mysql database around 20GB

I need to host a single machine database (constraints), wherein the database size is roughly 20gb. Most of the tables are in MyISAM. Any way I can actually run it with decent speed ? Alternatives I ...
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1answer
29 views

RDS Replication Error (Apply Error 1406 / Truncation)

I have a MySQL RDS instance as a master, created a Read Replica from it, and ran some schema change operations on it. To be specific, I changed the charset and collation of all the tables and columns ...