Ruby on Rails interview questions

ror_interview_questions.md

Ruby

• What is eigenclass ?

• Module and class (difference and when to use)?

• 'class_evel', 'module_eval' and 'instance_eval'(explain and difference, when to use)?

• Difference between 'each' and 'map'.

• Difference between 'find' and 'select'.

• 'delegate' in ruby.

• Single qoute('') vs Double qoute ("")

• Bang operate(!) differences.

• instance variable vs Class variable?

• Is ruby pure OOPS?

• extend Vs include?

• Difference between multiple and multi level inheritence?

• How to implement multiple inheritence?

• Super keyword?

• instance method Vs class method?

• Public class method?

• What is block?

• How do you create proc?

• difference between symbol and string.

• variable VS symbol.

• Write a program to print this pattern N = 7. So value of N is dynamic. If N is 6 or 5 then it should scale accordingly

  7

  7 6

  7 6 5

  7 6 5 4

  7 6 5 4 3

  7 6 5 4 3 2

  7 6 5 4 3 2 1

  7 6 5 4 3 2

  7 6 5 4 3

  7 6 5 4

  7 6 5

  7 6

  7

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Rails Questions

• Difference between empty? and blank?.
• Rails feature(https://blog.engineyard.com/2013/rails-4-changes), russian doll caching
• Difference between 'observer' and 'callbacks'. When to use?
• What is session and why we need it? (http://guides.rubyonrails.org/security.html#sessions)
• delayed_job and table column of it? ()
• Active jobs
• schedular (https://github.com/javan/whenever)
• 'includes' query in rails.
• Active Record Transactions (http://api.rubyonrails.org/classes/ActiveRecord/Transactions/ClassMethods.html)
• HashWithIndifferentAccess (http://api.rubyonrails.org/v4.2/classes/ActiveSupport/HashWithIndifferentAccess.html)
• 'after_commit' vs 'after_save'
• Specific gem?
• Forum or sites to get update?
• Usecase for 'yield' a block?
• Assets pipeline
• SOAP and REST API
• Web services and AWS web services
• how to move app from one server to other server
• Session management
• How to call procedure(SQL) in Rails

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DB

• Advantages of MongoDB

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SQL

• Difference between 'union' and 'union_all'. (http://java67.blogspot.in/2014/09/difference-between-union-vs-union-all-in-SQL.html)
• Inner join and left outer join
• Primary key and unique key
• Write query for: Table Name - Employee

EMPLOYEE_ID	FIRST_NAME	LAST_NAME	SALARY	JOINING_DATE	DEPARTMENT_ID
1	Michel	Clarke	1000000	01-JAN-14 11.00.00 AM	1
2	Ricky	Charma	800000	05-JAN-14 11.00.00 AM	2
3	Michel	Farma	700000	05-FEB-14 11.00.00 AM	3
4	Lasith	Karma	600000	03-APR-14 11.00.00 AM	1
5	Trish	Dharma	650000	15-JUNE-14 11.00.00 AM	2
6	Mike	Sharma	700000	04-AUG-14 11.00.00 AM	4
7	Lees	Monte	650000	02-SEP-14 11.00.00 AM	4
8	Clees	Clarke	600000	03-NOV-14 11.00.00 AM	3

Table Name – Department

DEPARTMENT_ID	DEPARTMENT_NAME
1	Programming
2	Billing
3	TestingG
4	Sales
5	Designing

Get department name and department wise average salary from employee and department table order by salary ascending?

Desired output

Dept Name	Avg Salary / Dept
Programming	200000
Billing	100000
TestingG	800000
Sales	900000
Designing	400000

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Javascrip/Jquery

• Difference between 'find' and 'closest'
• bind Vs live

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HR

• What is determination
• If you would have a conflicts with co-worker related to one solution, your solution is good then what will you do?