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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964 views

Problems migrate database from 4 to 5.5 mysql

I have a server with 4.0 mysql version innodb engine. I need to migrate to other server with 5.5 version (linux) ok I dump the full database using mysqldump, when i try to restore on the 5.5 ...
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1k views

Define a column as MD5 sum of other columns in MySql

Suppose I have following table - id name -- ---- 1 kshitiz Is it possible to define another column that is the md5 sum (or some other hash) of values in the previous two columns? id ...
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2answers
62 views

Guaranteeing a FK relationship through multiple tables

I'm using MySQL / InnoDB, and using foreign keys to preserve relationships across tables. In the following scenaro (depicted below), a 'manager' is associated with a 'recordLabel', and an 'artist' is ...
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1answer
143 views

MySQL Cluster - strange syntax error

I have MySQL Cluster instance and want one column (BLOB) to be stored on disk instead of memory. I tried to follow this tutorial: http://mikaelronstrom.blogspot.com/2006/02/how-to-define-table-that-...
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1answer
50 views

Query Optimization for added value

I have a query that's behaving a bit oddly. In my database I have a table called "records". It tells me a bunch of information about what applications a user ran on my company's machines. I'm ...
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2k views

What permissions do you need to take a mysql database backup via SSH?

are 'SELECT' and 'LOCK' privileges enough for a 'mysql database user' to take a full database backup via SSH? I am able to take a backup using these privileges, but unsure if I am backing up all the ...
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65 views

strange “using where” in simple query

I have a table with this structure: mysql> describe user_groups; +----------+----------------------+------+-----+---------+----------------+ | Field | Type | Null | Key | ...
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1answer
665 views

Restoring old MySQL database settings

I know this question may be similar to some others posted but think it may be slightly different, so hopefully it's ok. Basically I just reinstalled Windows as I bought a new HD and I am in the ...
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1answer
530 views

MySQL MyISAM index causes query to match no rows; indexes disabled, rows match

I created a table and index as described in this SE post, but when I query the table for a particular ID, no matches are found. When I disable the index, matches are found. Commands ran: CREATE ...
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128 views

MySQL data retained after OS reinstall

Something strange happened today. I reinstalled my OS and then when I reinstalled MySQL workbench some of my old data was still there. I think the actual local db is empty, but all the connections, ...
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785 views

difference between MySQL and noSQL databases [duplicate]

All these days I've been using MySQL, recently I saw a kind of similar named Database NoSQL. What is NoSQL and what is the difference between them ?
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994 views

my.cnf validation [closed]

We have moved our server from old 8 GB RAM Server to new 16 GB RAM server so that we could have better performance. The server is still consuming lot of MEMORY. The tables in the database are not ...
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2answers
40 views

How to optimise this Mysql query

How do I optimise this query . Its taking long time. The inner query is fine. But outer query is taking more time . Please guide.Have attached the explain output. SELECT users.ID, IFNULL( CONCAT( ...
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380 views

Query to get reposts from people the user is following

I have a table posts where all the posts by users are stored, the structure of this table is as follows. | post_id | post_user | post_content | post_date | The users table is as follows. | user_id ...
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1answer
454 views

Database design for surveys in MySQL

I'm trying to design an app where users take a new survey everyday (that's not the main part of app but it's an important part). I've never designed a database before so what I'm trying to do might ...
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1answer
148 views

Optimizing and maintaining test databases for a web development team

Right now when we test, we mysqldump from the production database, load it into the test database server, and then use scripts to scrub sensitive data. As the database is getting bigger, this process ...
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2answers
389 views

MySQL row does not persist, but primary key with auto-increment is incremented

I have a MySQL database that is acting oddly. I insert a new row and observe that for a brief period of time (less than 30 seconds), the row persists as expected in the table. After this time, though, ...
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1answer
952 views

PHP MySQL library version 5.0.51a differs from your MySQL server version 5.1.61

After asking last question about $id=$_GET['id']; and security issues I tried a PDO connection to my server. The following message appeared; ERROR: could not find driver. I connected to phpMyAdmin - ...
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1answer
84 views

MyISAM table is not working as expected in MySQL

mysql>show processlist; +-------+------+------------------------------+---------------------+---------+-------+-------+------------------+ | Id | User | Host | db ...
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1answer
327 views

MySQL Replace function throwing error

I am trying to update ^G (Ctrl G) in a table, below is scenario- CREATE TABLET TEST(COLA INT,DESCRIPTION VARCHAR(20)); I have crtl G in my data for description field, so to replace it with a \,I am ...
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1answer
795 views

Mysql federated engine table creation error

I am trying to create a federated table on my local machine which suppose to connect to my another machine which also in my local network. I have enabled federated engine on both machines and is shown ...
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1answer
1k views

Event Management System

I'm working on a "Event Management System" Online Software Project where the system requires the following: Viewers can sign up for their user account Events can be created by the admin from the ...
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1answer
376 views

Mysql Select query takes too long for mutilple tables - 12 minutes

Mysql query almost takes more than 12 minutes though indexing is in place. Please can you throw some light on how to bring down the response time. Thanks select count(*) from IMSI t1 USE INDEX(...
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1answer
1k views

Export just rows modified in last month (date defined by user)

I'm asking if it's possible in MySQL to export just rows modified in a period of time for example in the past month, if it is possible, how?
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1answer
159 views

Foreign key in MySQL

I am learning about database, I need to know something about the foreign key in MySQL. Consider the following two tables. UserGroupType. UserGroup. UserGroupType: UserGroup: In this table ...
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2answers
545 views

MySQL stored procedure create database by month

I'm a systems admin, and I'm not a dba, I'm wondering if I could use MySQL stored procedure to Query main database and move records by month to another database located on the same system. This ...
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2answers
3k views

Order table Database design

I'm in need of some help with the database design of order table of a shopping cart for online food ordering system. I have a design below. Tables about which I'm Concerned are order_details and ...
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2answers
4k views

Difference between two recordsets

I'm looking to calculate the difference between two record sets in MySQL. Say I have the following table: colname type attrbutes id uInt PK date date PK count uInt With this data: id ...
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1answer
143 views

Database design in MySQL

I am designing a database for an web application, in this system there are multiple users. Consider, Public (Buyer). Merchant. Tele Marketing Executive(TME). Marketing Executive(ME). Lead Generator.....
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2answers
513 views

MySQL database datafiles in windows SystemData directory

When I create a database and some tables in MySQL Server, it makes some data files in Windows SystemData directory in C:\ProgramData\MySQL\MySQL Server 5.5\data\mydb\. Each table has three files with ...
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1answer
354 views

Information about Disk Storage MySQL

I am trying to create an application for monitoring MySQL,in my application there's a part of monitor DISK STORAGE, so after more research I have not found how to calculate : used and free size of ...
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1answer
1k views

Can't change root password: “The system cannot find the file specified.”

I'm trying to change the root password in MySQL on my development machine (I've just installed MySQL, so it currently doesn't have a password), but it keeps failing with the following error message: ...
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1answer
134 views

Maintain stable data in a database

I am doing Performance evaluation of my application. The size of database is around 20GB. I am using jMeter as a performance evaluation tool. Here each performance test (ie., Each jMeter run) there is ...
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1answer
618 views

Does this error message indicate a SQL injection vulnerability?

I just took over management for a webservice and today I got a user report about this error. Now I'm no sql injection expert but does this error make this attack possible? Microsoft OLE DB Provider ...
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1answer
502 views

MySQL system date change impact

I can't find an answer for this problem. If I have in my database data of datatypes like date and timestamp. Can the change of system date affect this saved data ? I mean, can these existing ...
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1answer
129 views

csv file handling

I am using an EAV like structure to store CSV files. There aren't any predetermined columns, so it needs to be able to expand the columns / data on demand. Is this a fairly good way of handling such a ...
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1answer
216 views

Chaining System Query in MySQL

I have a table which maintains a user chain Here is the table structure +------+--------+ | id | user | +------+--------+ | 2 | 4 | | 10 | 4 | | 11 | 4 | | 1 | 2 | |...
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1answer
838 views

MySQL query optimizer ignoring smaller scan on TIMESTAMP column, cardinality?

I've got a complex multi-join query where the optimizer won't pick an index on a TIMESTAMP column even though it results in a smaller index/table scan. If I force the index on the TIMESTAMP column, ...
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1answer
213 views

How we take dump with batch of records option?

we have 30 GB database.we want to take backup of this database. here the question is we want to take the backup batch of every 10k records. How we can take batch of records backup using mysqldump
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1answer
85 views

MySql Replication in two directions

I am successfully able to set up master-slave replication of database with MySQL. So, whenever I am updating my database on master, It will automatically replicated on the slave. Now, I have situation ...
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1answer
928 views

Is there a system wide way to change MariaDB to create tables using ROW_FORMAT = DYNAMIC

I've got a 700MB dump file from a mysql database that I was trying to undump into a new install of MariaDB and I got this error ERROR 1118 (42000) at line 7481: Row size too large (> 8126). ...
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2answers
80 views

What is the best way to transport database fields from one database to another?

I have two databases. The table name and fields name are different and field numbers are unequal. I need to transport all fields from one database to another. I can import the database as CSV format. ...
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2answers
3k views

Error Code : 1248 Every derived table must have its own alias in MySQL

i have problem here, when im trying to select with query below, i got error message Error Code : 1248 Every derived table must have its own alias SELECT B.BRANCH_CODE, B.BRANCH_NAME, C....
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1answer
656 views

MySQL - What is the diffrence between ClearText authentication and PAM authentication plugins?

PAM Authentication: PAM enables a system to use a standard interface to access various kinds of authentication methods, such as Unix passwords or an LDAP directory. Cleartext Client-Side ...
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1answer
127 views

MySQL HDD activity with empty process list

What does this mean and how can I understand what is mysql doing? I use InnoDB, my database is huge. This happens when I disconnect my app. Thanx.
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1answer
3k views

InnoDB tables inaccessible after reboot

After reboot each time, I can't see my InnoDB table. However, when use command mode I can see my tables, but cannot access to it. mysql> show tables; +----------------------+ | ...
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1answer
322 views

Implementing something similar to “pointer arrays” with MySQL

While building a site I came across the following issue: I want to be able to have multiple containers and within each container have ids pointing to multiple items that lie on another table. Scheme: ...
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1answer
2k views

User roles and permissions

Look at the attached graphic. I'm trying to keep this as simple as possible. Basically I want to have multiple admins(or superusers) who own regular users who own sites. Admins can give regular ...
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2answers
708 views

what happens when InnoDB logspace is too small

I've just seen several mysql errors in my log: InnoDB: ERROR: the age of the last checkpoint is X InnoDB: which exceeds the log group capacity Y I understand, that I do have to increase the ...
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1answer
42 views

FILE privilege still allows for file writing on server (localhost)

I created a user without the FILE privilege, and a web app connected to the DB with this user is still able to write text files on my localhost. To write these files, the program just uses fopen and ...