Explore information related to databases


MySQLdump: Got error: 1044 when selecting the database - Fix it Now ?


This article covers methods to resolve MySQLdump: Got error: 1044 when selecting the database. 

When this error happens, you will get an error message such as this:

mysqldump: Got error: 1044: Access denied for user ‘root’@’localhost’ to database ‘information_schema’ when using LOCK TABLES


To fix this MySQLdump error: 

1. You can pass the –single-transaction option to mysqldump command:

$ mysqldump --single-transaction -u user -p DBNAME > backup.sql

2. Also, you can simply grant LOCK TABLES to your user:

$ mysql -u root -p

And type:

mysql> GRANT SELECT,LOCK TABLES ON DBNAME.* TO 'username'@'localhost';

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Advantages of NoSQL Databases - Get to know them now


This article covers the advantages of NoSQL Databases. #SQL databases are vertically scalable, NoSQL databases are horizontally scalable. SQL databases are table based, while NoSQL databases are document, key-value, graph or wide-column stores. 

SQL #databases are better for multi-row transactions, #NoSQL are better for unstructured data like documents or JSON.

#MongoDB, CouchDB, CouchBase, Cassandra, HBase, Redis, Riak, Neo4J are the popular NoSQL databases examples.

The structure of many different forms of data is more easily handled and evolved with a NoSQL database. 

NoSQL databases are often better suited to storing and modeling structured, semi-structured, and unstructured data in one database.


Main purpose of NoSQL?

NoSQL Database is a non-relational Data Management System, that does not require a fixed schema. 

It avoids joins, and is easy to scale. 

The major purpose of using a NoSQL database is for distributed data stores with humongous data storage needs. 

NoSQL is used for Big data and real-time web apps.


Reasons to Use a NoSQL Database includes:

1. Storing large volumes of data without structure. A NoSQL database doesn't limit storable data types.

2. Using cloud computing and storage. Cloud-based storage is a great solution, but it requires data to be easily spread across multiple servers for scaling.

3. Rapid development.


Main types of NoSQL databases?

There are four big NoSQL types: 

1. Key-value store

2. Document store, 

3. Column-oriented database,

4. Graph database. 

Each type solves a problem that can't be solved with relational databases. 

Actual implementations are often combinations of these. 

OrientDB, for example, is a multi-model database, combining NoSQL types.

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MongoDB failed to load list of databases - Fix it now


This article covers how to resolve the error 'MongoDB failed to load the list of databases' can occur due to various reasons that include failed database user/password authentication, outdated Robo 3T version, and so on.

The error 'MongoDB failed to load the list of databases' means that you can't connect if there are no databases to list. 


To fix the error 'MongoDB failed to load the list of databases':

1. You can fix this issue with 1.2 connecting to a new mongo 4.2.

It's fixed when using robo3t version 1.3, which supports newer version of mongo.

2. You can create a database and a collection for it. 

Once you create a database and a collection, it works.

3. You will need to upgrade mongodb to the last version, so you can to connect in your local database.

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MongoDB error network is unreachable - Fix it now


This article covers methods to resolve the error 'MongoDB error network is unreachable' which can occur due to many reasons that include network issues, if the mongo server is not started, and so on.

To resolve this #MongoDB #error:
1. On Ubuntu server, to open mongo shell run:

$ mongo

2. Inside mongo shell, type following command to create new a admin user.

> use admin;
> db.createUser({user:"admin", pwd:"password", roles:[{ role: "root", db: "admin" }]});

3. By default mongodb is configured to allow connections only from localhost(IP 127.0.0.1).
We need to allow remote connections from any ip address. The following change should only be done in your development server. Open up etc/mongod.conf file and do the following change.

# network interfaces
net:
port: 27017
bindIp: 0.0.0.0   #default value is 127.0.0.1


Also in the same mongod.conf file uncomment security option and add authorization option as shown below:

security:
authorization: enabled    


4. Save and exit the mongod.conf file and restart mongodb server:

$ sudo servcie mongod restart

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Executing queries from the MySQL Command Line


This article will guide you on how to run queries from the 3MySQL command line. The MySQL #Command Line Tool is a useful way to run #queries from the command line. It’s easy to run select queries and display the results in either a horizontal or vertical format, and the queries run are kept in a history file which you can navigate through. 

If you don't want to run a particular query after all you can use the c command to clear it.

The most common way to get a list of the MySQL #databases is by using the mysql client to connect to the MySQL server and run the SHOW DATABASES command. If you haven't set a password for your MySQL user you can omit the -p switch.

To Connect to a MySQL Database:

1. Click Services tab.

2. Expand the Drivers node from the Database Explorer.

3. Enter User Name and Password.

4. Click OK to accept the credentials.

5. Click OK to accept the default schema.

6. Right-click the MySQL Database #URL in the Services window.

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Orphaned users in SQL Server


This article will help you to identify #Orphaned #Windows #Logins and Groups in #SQL Server.
To Resolve an Orphaned User:
To map an orphaned user to a login which already exists in master, execute the ALTER USER #statement in the user database, specifying the login name.
ALTER USER <user_name> WITH Login = <login_name>; When you recreate a missing login, the user can access the database using the password provided.
To fix orphaned users for all databases in SQL Server:
1. Login with same name as user exists – generate ALTER LOGIN to map the user to the login.
2. No login with same name exists – generate DROP USER to delete the orphan user.
3. Orphan user is [dbo] – change the database owner to SA (or whatever SA was renamed to).

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How To Connect to a Redis Database Different ways to do it


This article will guide you on the steps to connect to a #Redis #database using different commands like redis-cli using #commands.

Running redis-cli followed by a command name and its arguments will send this command to the Redis instance running on localhost at port 6379. You can change the host and #port used by redis-cli, just try the --help option to check the usage information.

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Recovering a database from suspect mode in SQL


This article will guide you through the process of repairing  a database which is in Suspect mode in SQL by performing consistency check on database in emergency mode and executing ALLOW DATA LOSS in single user mode.

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Solve phpMyAdmin Timeout error 1440 session


We have dealt with numerous cases of MySQL and phpMyAdmin Errors and support request from our customers regarding Databases related errors as part of our Linux Support Services.

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How to fix Horde Fatal Error


Fatal Error in Horde Webmail is experienced by most users when they are about logging into their Email.

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Easy fix to SQL error 5023


From time to time, we do receive SQL related server bugs queries of which one of it was "SQL error 5023".

This SQL error is very catastrophic and it tends to disrupt the SQL server when it is trying to start up.


To fix SQL Server Error 1225:

1. Click WindowsKey + R and enter services. msc.

2. Once Services opens scroll down and locate service SQL Server.

3. Highlight the service and click START.

4. Wait for the service to start and retry to connect to your MSSQL instance.

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