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Q:

Explain Not Null constraint.

Answer

Oracle NOT NULL is used on a column to ensure that the value for that column can never be NULL.
Example:
Below, the constraint is that the id should never be NULL. If it is, oracle throws an error.
create table employee ( id number NOT NULL, Name varchar(200) );

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Subject: Oracle

Q:

What are the uses of synonyms?

Answer

- Mask the real name and owner of an object.
- Provide public access to an object
- Provide location transparency for tables, views or program units of a remote database.
- Simplify the SQL statements for database users.

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Subject: Oracle

Q:

What is a synonym? What are its various types?

Answer

A synonym can be called as an alias for a table, view, sequence or program unit. It is basically of two types:
- Private - Only the owner can access it.
- Public - Can be accessed by any database user.

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Subject: Oracle

Q:

Explain the difference between star and snowflake schemas.

Answer

Star schema: A highly de-normalized technique. A star schema has one fact table and is associated with numerous dimensions table and depicts a star.


Snow flake schema: The normalized principles applied star schema is known as Snow flake schema. Every dimension table is associated with sub dimension table.


 


Differences:


- A dimension table will not have parent table in star schema, whereas snow flake schemas have one or more parent tables.


- The dimensional table itself consists of hierarchies of dimensions in star schema, where as hierarchies are split into different tables in snow flake schema. The drilling down data from top most hierarchies to the lowermost hierarchies can be done.

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Subject: Data Warehousing

Q:

What is the difference between Notify URL and Return URL?

Answer

Notify URL and Return URL is used in Paypal Payment Gateway integration. Notify URL is used by PayPal to post information about the transaction. Return URL is used by the browser; A url where the user needs to be redirected on completion of the payment process.

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Subject: PHP

Q:

Differentiate different types of Doctypes from one another.

Answer

Doctype helps the web browser to correctly render the web pages. There are different types of Doctype that are available and they are as follows:


=> Strict Doctype: it consists of all the HTML elements and it is also known as DTD (Document type definition) but it doesn't include the presentational and deprecated elements i.e. font, center, etc. Framesets related elements are also not allowed in this. For example:


<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"


"https://www.w3.org/TR/html4/strict.dtd">


=> Transitional Doctype: it consists of all the HTML elements and attributes. It is also known as DTD (Document type definition). It includes the presentational and deprecated elements i.e. font, center, etc. Framesets related elements are also not allowed in this. For example:


<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"


"https://www.w3.org/TR/html4/loose.dtd">


=> Frameset Doctype: it consists of all the HTML elements and attributes. It is also known as DTD (Document type definition). It includes the presentational and deprecated elements i.e. font, center, etc. Framesets related elements are also allowed in this. For example:


<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN"


"https://www.w3.org/TR/html4/frameset.dtd">

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Subject: Web Technology

Q:

Explain Non Breaking space in HTML.

Answer

When we add many spaces in the content then HTML remove all space except one space this is Non Breaking Space. To overcome this problem we use “&nbsp”. Suppose we want to add 3 space between two words then we have to use &nbp three time. 


 

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Subject: Web Technology

Q:

What happens if the list-style-type property is used on a non-list element like a paragraph?

Answer

Here the property will be ignored without having any effect on the paragraph.

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Subject: Web Technology