ETL - What is Entity relation?? How is works with Datawarehousing ETL modeling???

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What is Entity relation?? How is works with Datawarehousing ETL modeling???

Total Answers and Comments: 3

Last Update: December 21, 2006 Asked by: Shobhit

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August 29, 2006 07:50:15

Rangini vignesh

RE: What is Entity relation?? How is works with Datawa...

Ans:Entity is nothing but an Object, it has characteristics.We call entity in terms of Logical view.The entity is called as a table in terms of Physical view.

The Entity relationship is nothing but maintaining a primary key,foreign key relation between the tables for keeping the data and satisfying the Normal form.

There are 4 types of Entity Relationships.

1.One-One,

2.One-Many,

3.Many-One,

4.Many-Many.

In the Datawarehouse modeling Entity Relationship is nothing but,a Relationship between dimension and facts tables(ie:Primary,foreign key relations between these tables).

The fact table getting data from dimensions tables because it containing primary keys of dimension tables as a foreign keys for getting summarized data for each record.

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October 23, 2006 22:44:30

thumatinagaraju

Member Since: October 2006 Contribution: 26

RE: What is Entity relation?? How is works with Datawa...

Entity is nothing but an object usually it is table containing the attributes(columns)ETL is a tool not a modeling .. it's useful for transfrering the data from the sources (hetogeniuos) to the target (warehouse) modeling is much useful for forming the fact's and dimension's which are used for decision making process using OLAP tools after forming the warehouse.

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December 21, 2006 14:41:35

prav2000

Member Since: December 2006 Contribution: 5

RE: What is Entity relation?? How is works with Datawa...

Majority of the times the DataWareHouse core tables are in a 3NF form and this is where your entity relationship comes into picture.

Further you can have fact and dimension tables which are populated using the core tables. The fact and dimension tables follow the star schema or snow flake schema.

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