Ruby Introduction

Ruby Introduction

Ruby is a general-purpose, interpreted and pure object-oriented programming language.

It was created in 1993 by Yukihiro Matsumoto of Japan.

Ruby Features:

It is an open-source and is free.

Interpreted programming language.

True object-oriented programming language.

Server-side scripting language.

Common Gateway Interface (CGI) scripts.

Ruby code can be embedded into Hypertext Markup Language (HTML).

Very much scalable and easily maintainable.

Used to develop the Internet and intranet applications.

Support many GUI tools such as Tcl/Tk, GTK, and OpenGL.

Supports to connect databases like DB2, MySQL, Oracle, and Sybase.

How to install ruby package ?

Follow this link to install ruby on your machine.

Ruby First Program

#!/usr/bin/ruby -w
puts "First Program!";

Run program use the ruby command

$ruby test.rb

Output:

prints the result

First Program!

Strings with multiple lines:

#!/usr/bin/ruby -w

print <<EOF
line1
line2
EOF

Output:

line1
line2

Same as above, in other way.

#!/usr/bin/ruby -w
print <<"EOF";
line1
line2
EOF

Output:

line1
line2

To execute and print multiple commands.

#!/usr/bin/ruby -w
print <<`EOC` # execute commands
echo 'line1'
echo 'line2'
EOC

Output:

line1
line2

Connects Postgresql database in ruby code:

		rows=Array.new
		con = PG.connect :host => 'host_name', :dbname => 'database name', :user => 'db user name', :password => 'db user password' 
		rs = con.exec "select emp.first_name || ' ' || emp.last_name as employee_name,"+
				"emp.start_date, emp.end_date, dp.designation, emp.salary, emp.email "+
				"from employees emp "+
				"join department dp on (emp.employee_id = dp.employee_id) "+
				"where dp.department_id = '2';"
		rs.each do |row|
			obj = { "name" => row['employee_name'],"start_date"=>row['start_date'],"end_date"=>row["end_date"],"designation"=>row['designation'],"salary"=>row['salary'],"email"=>row['email']};
			rows.push(obj)
		end
    
		rescue PG::Error => e
			#rows.push(e.message)
			puts e.message   
		ensure
	    		rs.clear if rs
	    		con.close if con

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