Interview Questions

CONSTRUCTOR : PHP allows developers to declare constructor methods for classes. Classes which have a constructor method call this method on each newly-created object, so it is suitable for any initialization that the object may need before it is used.

DESTRUCTORS : PHP 5 introduces a destructor concept similar to that of other object-oriented languages, such as C++. The destructor method will be called as soon as all references to a particular object are removed or when the object is explicitly destroyed or in any order in shutdown sequence.

Windows XP supports four major file systems: FAT12, FAT16, FAT32 and NTFS. This means that Windows XP can be installed on these file systems. The use of NTFS is preferred especially when using a bigger hard drive space.

The mapreduce framework contains most of the key architecture principles of cloud computing such as:

- Scale: The framework is able to expand itself in direct proportion to the number of machines available.

- Reliable: The framework is able to compensate for a lost node and restart the task on a different node.

- Affordable: A user can start small and over time can add more hardware.

An XSL sheet or a document may have duplicate elements and attributes. Therefore, the XML namespaces define a way to distinguish between duplicate element types and attribute names.

An XML namespace is a collection of element type and attribute names. It is a URI due to which any element type or attribute name in an XML namespace can be uniquely identified. 

It consists of two parts : the name of the XML namespace and the local name.

e.g.: xmlns: h=”https://www.abc.com”

After this, you can write

<h:table>

……..

</h:table>

to associate the table with the declared namespace. 

They communicate via service MVS request calls.

Inheritance is the ability to create new classes based on existing classes. It is useful to reuse existing code.

The foreground activity, being the most important among the other states, is only killed or terminated as a last resort, especially if it is already consuming too much memory. When a memory paging state has been reach by a foreground activity, then it is killed so that the user interface can retain its responsiveness to the user.

A database trigger is procedural code that is automatically executed in response to certain events on a particular table or view in a database. The trigger is mostly used for maintaining the integrity of the information on the database.

Syntax:

CREATE OR REPLACE TRIGGER [Trigger Name] [Before / After / Instead Of]

ON [schema].[table]

<PL/SQL subprogram>

Types of PL/SQL triggers : 

> Row trigger          - The trigger fires for each ROW affected.

> Statement trigger - The trigger is fired once when the condition is matched

> Before and After trigger - The BEFORE trigger run the trigger action before the insert, update or delete statement. The AFTER trigger runs the trigger action after the insert, update or delete statement is executes.