Interview Questions

A foreign key is a reference to another table. It is used to establish relationships between tables. For example, relationship between employee and professor table. One employee can have multiple professors. The Primary key of employee becomes foreign key of professor.
Example:
create table employee ( id number NOT NULL, professor_id NOT NULL, Name varchar(200) Constraint prim_id Foreign key(id) references professor(professor_id) );

The diamond problem is an ambiguity that can occur when a class multiply inherits from two classes that both descend from a common super class

A collection just like an array is an ordered group of elements of the same type. Each elements position is determined by a unique subscript.

Index by tables:- They are similar to hash arrays that allows to search for subscript values using arbitrary numbers and strings.

They can be declared as:

TYPE type_name IS TABLE OF element_type [NOT NULL]

INDEX BY [BINARY_INTEGER | PLS_INTEGER | VARCHAR2(size_limit)];

INDEX BY key_type;

Example:

TYPE studenttyp IS TABLE OF emp%ROWTYPE

INDEX BY BINARY_INTEGER;

stud_tab studenttyp;

Nested tables:- they hold random number of elements and use sequential numbers as sub scripts.

They can be declared as:

TYPE type_name IS TABLE OF element_type [NOT NULL];

Example: TYPE employee_type IS TABLE OF NUMBER INDEX BY VARCHAR2(64);

Varrays: Holds a fixed number of elements which can be changed in run time. 

They can be declared as:

TYPE type_name IS {VARRAY | VARYING ARRAY} (size_limit) OF element_type [NOT NULL];

Example: TYPE Calendar IS VARRAY(366) OF DATE;

As far PHP concern it only support single Inheritance in scripting. we can also use interface to achieve multiple inheritance.

You should not use AJAX if:

             =>  You want the page to show in a search engine, such as Google, because WebCrawler does not execute JavaScript code.

             =>  The browser does not support JavaScript.

             =>  You want to create a secure application.

Generally a business analyst covers several stages in Software Development Life Cycle.

Like:  Client Consulting, Client Requirement Study, Planning for business needs, Business Requirement Documenting, Work on functional requirement, Prepare test data with inputs from end users, Document use case scenarios, Help Testing team with test plan and testing, Help end users with user acceptance testing UAT, Go live and post production support tasks.

Separation of an employee exists when the service of an employee comes to an end because of one reason or other. "Separation of employment" refers broadly to the process of managing the termination of employment. It is a sensitive issue for any organization. 

Types of separation:

1) Volunntary:

a) Resignation
b) Job abandonment
c) Retirement

2) Involuntary:

a) Layoff
b) Dismissal
c) Plant closure
d) Death or Disability.

A31. The self-referencing constraint limits in a single table the changes to a primary key that the related foreign key defines. The foreign key in a self referencing table must specify the DELETE CASCADE rule.