Getting Started with MySQL

This is a simple beginners guide to use MySQL in linux, from installation to querying the databases.
  1. Installation
  2. Login
  3. Databases and tables

Installation

First let's make sure our package management tools are up-to date. For that run the following commands in command line.

sudo apt-get update
sudo apt-get dist-upgrade
Once it finishes update and upgrading, we can install MySQL with following command.
sudo apt-get install mysql-server mysql-client
This will take a moment to install and now we are ready to go. 

Login

At first start up MySQL server is not set up with a password for root and we can login with,
mysql -u root -p
If we are setting the password for the first time we can use following to set-up,
mysqladmin -u root -p NEWPASSWORD  
If we want to change a previously set password following command can be used,
mysqladmin -u root -p'oldpassword' password newpassword

Databases and Tables

First we should login to MySQL server with,
mysql -uroot -p<password>
Then it will point us to mysql console as follows where we can run queries,
mysql>
To see the available databases,
show databases;

To see the available tables inside a database,
use <database_name>;
show tables;
To see the field formats of the table,
describe <table_name>;
To delete database/tables,
drop database if exists <database_name>  (for a table use table name)
Just like that, we can also run SQL queries like "SELECT * FROM user;" which will print the result in console.

If we have an .sql script to set up the databases or tables, we can just run it with,

source <path_to_script_file>;


If we want to import a large database then following is recommanded,
mysql -u root -p database_name < database_dump.sql
Cheers!

Popular posts from this blog

Signing SOAP Messages - Generation of Enveloped XML Signatures

Image
Digital signing is a widely used mechanism to make digital contents authentic. By producing a digital signature for some content, we can let another party capable of validating that content. It can provide a guarantee that, is not altered after we signed it, with this validation. With this sample I am to share how to generate the a signature for SOAP envelope. But of course this is valid for any other content signing as well. Here, I will sign The SOAP envelope itself An attachment  Place the signature inside SOAP header  With the placement of signature inside the SOAP header which is also signed by the signature, this becomes a demonstration of enveloped signature. I am using Apache Santuario library for signing. Following is the code segment I used. I have shared the complete sample here to to be downloaded . public static void main(String unused[]) throws Exception {         String keystoreType = "JKS";         Stri...
Read more

Tomcat JDBC Pool - Connection Leak - Catch the Culprit

Database connection leaks are something that can stay hidden unless paid specific attention and would come to the surface at the most critical stages at a peak time of the system. We would manually check if all the open connections have been closed properly. Then we have various code quality plugins that would scan and check for that. Still when the connections are passed through a complex structure of program both of these can miss a possible connection leak. Then at unit test or integration test levels, we can have checks to validate the counts in the connection pool to avoid this unfortunate situation, that would keep engineers busy at year-end, black Friday, etc. :) In the unfortunate case of hitting with a performance degrade or a total crash of the system which can be propagated via a JDBC connection leak, when we suspect a connection leak, how easily and quickly isolate the culprit. In the Tomcat connection pool, we can do this using 3 properties. removeAbandoned If a...
Read more

How to convert WSDL to Java

Image
Background Basically WSDL (Web Services Development Language) is an XML document used to describe or locate web services. WSDL stands for Web Services Description Language. The document describes a Web service. It specifies the location of the service and the operations that can be taken.  WSDL2Java is distributed with Axis2 package of Apache and need to set-up Axis2 to use this service. A  guide to set-up Axis2  can be found in apache organization documents .WSDL 2.0 is the currently using version. Obviously JDK should be properly installed too. Note: For the 3rd method you are not needed to set these things by yourself. The WSDL document includes server Java programs for Web services and generated classes using WSDL2Java feature includes client stubs, server skeletons and data types that can help in writing client side. The generated stub classes play a great role in distributed computing and if you are interested can read on  what are...
Read more