Interview Questions

Prices do not reflect the full social cost of production is an example of Market failure.

A market failure occurs when the supply of a good or service is insufficient to meet demand. This results in an inefficient distribution of resources among market participants.

It also occurs if externalities are not accounted for.

If a firm fails to maximize its profits this is not a general market failure.

Dimensional modeling is often used in Data warehousing. In simpler words it is a rational or consistent design technique used to build a data warehouse. DM uses facts and dimensions of a warehouse for its design. A snow and star flake schema represent data modeling.

An SQL statement is a string of characters that conforms to the syntax and format specified in the international standard.

A query is a statement that returns a record-set.

Reserved words are words that cannot be used as object or variable names in a Java program because they're already used by the syntax of the Java programming language.

Java reserved words are keywords that are reserved by Java functions or other uses that cannot be used as identifiers (e.g., variable names, function names, class names).

If a reserved word was used as a variable you would get an error or unexpected result.

Examples : Int, Long, Abstract, Class, Break, Catch, Case, Public, Static, Void,...

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.

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.

UNION selects only distinct values whereas UNION ALL selects all values and not just distinct ones

Visual basic can be used for server side scripting. A component designed with Visual basic will not have any user interface instead provides the functionality of Active X to other programs via COM. This form of technique allows server side functionality and add in module.