Archive for the ‘MYSQL’ Category


MySQL and SQL Server are the two leading databases that support front end applications related to various domains. The differences between MySQL and SQL Server are listed below:

MySQL SQL Server
MySQL is available for free since MySQL is an open source. SQL Server is not an open source and payment has to be made to use SQL Server.
MySQL offers only updateable views. SQL Server offers indexed views which are much more powerful, performance wise.
MySQL does not support XML. SQL Server supports XML.
MySQL provides only table level security. SQL Server provides column level security.
MySQL does not offer any certification for security. SQL Server has C2 compliant certification. Database security is verified by third party.
Earlier versionsof MySQL does not support triggers. Only MySQL 5.0 supports triggers. SQL Server provides triggers.
User defined functions are not supported in MySQL. User defined functions are supported in SQL Server.
Cursor feature is not available in MySQL. Cursor feature is available in SQL Server.
Stored procedures and full join facility is not offered in MySQL. Stored procedures and full join facility are offered in SQL Server.
Import and Export functions have very limited support in MySQL. Import and export are extensively supported in MySQL.
Transaction support is very much limited in MySQL. Transaction support is extensively and fully offered in SQL Server.
Replication support is very much limited in MySQL. Replication support is extensively and fully offered in SQL Server.
Auto tuning is not supported in MySQL. Auto tuning is supported in SQL Server.
Job scheduling and profiling are not available in MySQL. Job scheduling and profiling are available in MySQL.
Online backup support and clustering support is limited in MySQL. Online backup support and clustering support is extensive and complete in SQL Server.
Log Shipping and Storage Area Network support is not available in MySQL. Log Shipping and Storage Area Network support is available in SQL Server.
OLAP Services, Data Reporting and Data Mining are not supported in MySQL. OLAP Services, Data Reporting and Data Mining are supported in SQL Server.
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Joins in MySQL

Posted: January 21, 2014 in Database, MYSQL, Php

This article was written in 2011 and remains one of our most popular posts. If you’re keen to learn more about MySQL, you may find this recent article on administering MySQL of great interest.

“JOIN” is an SQL keyword used to query data from two or more related tables. Unfortunately, the concept is regularly explained using abstract terms or differs between database systems. It often confuses me. Developers cope with enough confusion, so this is my attempt to explain JOINs briefly and succinctly to myself and anyone who’s interested.

Related Tables

MySQL, PostgreSQL, Firebird, SQLite, SQL Server and Oracle are relational database systems. A well-designed database will provide a number of tables containing related data. A very simple example would be users (students) and course enrollments:

‘user’ table:

id name course
1 Alice 1
2 Bob 1
3 Caroline 2
4 David 5
5 Emma (NULL)

MySQL table creation code:


CREATE TABLE `user` (
	`id` smallint(5) unsigned NOT NULL AUTO_INCREMENT,
	`name` varchar(30) NOT NULL,
	`course` smallint(5) unsigned DEFAULT NULL,
	PRIMARY KEY (`id`)
) ENGINE=InnoDB;

The course number relates to a subject being taken in a course table…

‘course’ table:

id name
1 HTML5
2 CSS3
3 JavaScript
4 PHP
5 MySQL

MySQL table creation code:


CREATE TABLE `course` (
	`id` smallint(5) unsigned NOT NULL AUTO_INCREMENT,
	`name` varchar(50) NOT NULL,
	PRIMARY KEY (`id`)
) ENGINE=InnoDB;

Since we’re using InnoDB tables and know that user.course and course.id are related, we can specify a foreign key relationship:


ALTER TABLE `user`
ADD CONSTRAINT `FK_course`
FOREIGN KEY (`course`) REFERENCES `course` (`id`)
ON UPDATE CASCADE;

In essence, MySQL will automatically:

  • re-number the associated entries in the user.course column if the course.id changes
  • reject any attempt to delete a course where users are enrolled.
important: This is terrible database design!

This database is not efficient. It’s fine for this example, but a student can only be enrolled on zero or one course. A real system would need to overcome this restriction — probably using an intermediate ‘enrollment’ table which mapped any number of students to any number of courses.

JOINs allow us to query this data in a number of ways.

INNER JOIN (or just JOIN)

SQL INNER JOINThe most frequently used clause is INNER JOIN. This produces a set of records which match in both the user and course tables, i.e. all users who are enrolled on a course:


SELECT user.name, course.name
FROM `user`
INNER JOIN `course` on user.course = course.id;

Result:

user.name course.name
Alice HTML5
Bob HTML5
Carline CSS3
David MySQL

LEFT JOIN

SQL LEFT JOINWhat if we require a list of all students and their courses even if they’re not enrolled on one? A LEFT JOIN produces a set of records which matches every entry in the left table (user) regardless of any matching entry in the right table (course):


SELECT user.name, course.name
FROM `user`
LEFT JOIN `course` on user.course = course.id;

Result:

user.name course.name
Alice HTML5
Bob HTML5
Carline CSS3
David MySQL
Emma (NULL)

RIGHT JOIN

SQL RIGHT JOINPerhaps we require a list all courses and students even if no one has been enrolled? A RIGHT JOIN produces a set of records which matches every entry in the right table (course) regardless of any matching entry in the left table (user):


SELECT user.name, course.name
FROM `user`
RIGHT JOIN `course` on user.course = course.id;

Result:

user.name course.name
Alice HTML5
Bob HTML5
Carline CSS3
(NULL) JavaScript
(NULL) PHP
David MySQL

RIGHT JOINs are rarely used since you can express the same result using a LEFT JOIN. This can be more efficient and quicker for the database to parse:


SELECT user.name, course.name
FROM `course`
LEFT JOIN `user` on user.course = course.id;

We could, for example, count the number of students enrolled on each course:


SELECT course.name, COUNT(user.name)
FROM `course`
LEFT JOIN `user` ON user.course = course.id
GROUP BY course.id;

Result:

course.name count()
HTML5 2
CSS3 1
JavaScript 0
PHP 0
MySQL 1

OUTER JOIN (or FULL OUTER JOIN)

SQL FULL OUTER JOINOur last option is the OUTER JOIN which returns all records in both tables regardless of any match. Where no match exists, the missing side will contain NULL.

OUTER JOIN is less useful than INNER, LEFT or RIGHT and it’s not implemented in MySQL. However, you can work around this restriction using the UNION of a LEFT and RIGHT JOIN, e.g.


SELECT user.name, course.name
FROM `user`
LEFT JOIN `course` on user.course = course.id

UNION

SELECT user.name, course.name
FROM `user`
RIGHT JOIN `course` on user.course = course.id;

Result:

user.name course.name
Alice HTML5
Bob HTML5
Carline CSS3
David MySQL
Emma (NULL)
(NULL) JavaScript
(NULL) PHP

I hope that gives you a better understanding of JOINs and helps you write more efficient SQL queries.

Courtesy: http://www.sitepoint.com/understanding-sql-joins-mysql-database/


How do I import a MySQL .SQL text file to MySQL database sever using command line or gui tools?

You can import a MySQL script (or .sql) file into MySQL server using

  1. Unix / Linux shell prompt.
  2. phpMyAdmin web based gui tool.

Unix / Linux shell prompt example

Copy a .sql file to a remote server using sftp or scp client:
$ scp foo.sql vivek@serer1.cyberciti.biz:~/
Login into a remote server using ssh client:
$ ssh vivek@server1.cyberciti.biz
Type the following command to import a .sql file:

 
mysql -u USERNAME -p -h localhost YOUR-DATA-BASE-NAME-HERE < YOUR-.SQL.FILE-NAME-HERE

In this example, import a ‘foo.sql’ file into ‘bar’ database using vivek as username:

 
mysql -u vivek -p -h localhost bar < foo.sql

phpMyAdmin

Login to phpMyAdmin. Open a web-browser and type phpMyAdmin url:
http://server1.cyberciti.biz/phpmyadmin/
In phpMyAdmin, choose the database you intend to work with from the database menu list (located on the left side).

phpMyAdmin Database SelectionFig.01: phpMyAdmin Database Selection

Choose the IMPORT tab > Click on Browse your computer “Choose file” > Select file > Choose Ok > Choose Go

phpMyAdmin Importing .SQL FileFig.02: phpMyAdmin Importing .SQL File