Top Banner
Decision Support and Data Warehouse
23

Decision Support and Data Warehouse. Decision supports Systems Components Data management function –Data warehouse Model management function –Analytical.

Dec 19, 2015

Download

Documents

Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Page 1: Decision Support and Data Warehouse. Decision supports Systems Components Data management function –Data warehouse Model management function –Analytical.

Decision Support and Data Warehouse

Page 2: Decision Support and Data Warehouse. Decision supports Systems Components Data management function –Data warehouse Model management function –Analytical.

Decision supports Systems Components

• Data management function– Data warehouse

• Model management function– Analytical models:

• Statistical model, management science model

• User interface– Data visualization

Page 3: Decision Support and Data Warehouse. Decision supports Systems Components Data management function –Data warehouse Model management function –Analytical.

On-Line Analytical Processing (OLAP)• The use of a set of graphical tools that

provides users with multidimensional views of their data and allows them to analyze the data using simple windowing techniques

• OLAP Operations– Cube slicing–come up with 2-D view of data– Drill-down–going from summary to more

detailed views– Roll-up – the opposite direction of drill-down– Reaggregation – rearrange the order of

dimensions

Page 4: Decision Support and Data Warehouse. Decision supports Systems Components Data management function –Data warehouse Model management function –Analytical.

Slicing a data cube

Page 5: Decision Support and Data Warehouse. Decision supports Systems Components Data management function –Data warehouse Model management function –Analytical.

Example of drill-down

Summary report

Drill-down with color added

Starting with summary data, users can obtain details for particular cells

Page 6: Decision Support and Data Warehouse. Decision supports Systems Components Data management function –Data warehouse Model management function –Analytical.

Excel’s Pivot Table

• Data/Pivot Table– Drilldown, rollup, reaggregation

Page 7: Decision Support and Data Warehouse. Decision supports Systems Components Data management function –Data warehouse Model management function –Analytical.

Data Warehouse• A subject-oriented, integrated, time-variant,

non-updatable collection of data used in support of management decision-making processes– Subject-oriented: e.g. customers, employees,

locations, products, time periods, etc.• Dimensions for data analysis

– Integrated: Consistent naming conventions, formats, encoding structures; from multiple data sources

– Time-variant: Can study trends and changes– Nonupdatable: Read-only, periodically refreshed

Page 8: Decision Support and Data Warehouse. Decision supports Systems Components Data management function –Data warehouse Model management function –Analytical.

Data Warehouse Design- Star Schema -

• Fact table– contain detailed business data

• Ex. Line items of orders to compute total sales by product, by salesperson.

• Dimension tables– Dimension is a term used to describe any category or subjects of

the business used in analyzing data, such as customers, employees, locations, products, time periods, etc.

– contain descriptions about the subjects of the business such as customers, employees, locations, products, time periods, etc.

– Example: A sold item related to many business subjects such as salesperson, customer, product and time period.

Page 9: Decision Support and Data Warehouse. Decision supports Systems Components Data management function –Data warehouse Model management function –Analytical.

Example:Order Processing System

Customer Order

Product

Has

Has

1 M

M

M

CID Cname City OID ODate

PIDPname

Price

RatingSalesPerson

Qty

Page 10: Decision Support and Data Warehouse. Decision supports Systems Components Data management function –Data warehouse Model management function –Analytical.

Star Schema

FactTableLocationCodePeriodCode

RatingPIDQty

Amount

LocationDimension

LocationCodeStateCity

CustomerRatingDimension

RatingDescription

ProductDimension

PIDPname

Category

PeriodDimensionPeriodCode

YearQuarter

Can group by State, City

Page 11: Decision Support and Data Warehouse. Decision supports Systems Components Data management function –Data warehouse Model management function –Analytical.

Snowflake Schema

FactTableLocationCodePeriodCode

RatingPIDQty

Amount

LocationDimension

LocationCodeStateCity

CustomerRatingDimension

RatingDescription

ProductDimension

PIDPname

CategoryID

ProductCategory

CategoryIDDescription

PeriodDimensionPeriodCode

YearQuarter

Can group by State, City

Page 12: Decision Support and Data Warehouse. Decision supports Systems Components Data management function –Data warehouse Model management function –Analytical.

The ETL Process

E

T

LOne, company-wide warehouse

Periodic extraction data is not completely current in warehouse

Page 13: Decision Support and Data Warehouse. Decision supports Systems Components Data management function –Data warehouse Model management function –Analytical.

The ETL Process

• Capture/Extract• Transform

– Scrub(data cleansing),derive– Example:

• City -> LocationCode, State, City• OrderDate -> PeriodCode, Year, Quarter

• Load and Index

ETL = Extract, transform, and load

Page 14: Decision Support and Data Warehouse. Decision supports Systems Components Data management function –Data warehouse Model management function –Analytical.

From SalesDB to MyDataWarehouse

• Extract data from SalesDB:– Create query to get the data– Download to MyDataWareHouse

• File/Import/Save as Table

• Transform:– Transform City to Location– Transform Odate to Period

• Query FactPC

• Load data to FactTable

Page 15: Decision Support and Data Warehouse. Decision supports Systems Components Data management function –Data warehouse Model management function –Analytical.

Star schema example

Fact table provides statistics for sales broken down by product, period and store dimensions

Dimension tables contain descriptions about the subjects of the business

Page 16: Decision Support and Data Warehouse. Decision supports Systems Components Data management function –Data warehouse Model management function –Analytical.

Star schema with sample data

Page 17: Decision Support and Data Warehouse. Decision supports Systems Components Data management function –Data warehouse Model management function –Analytical.

SQL GROUPING SETS

• GROUPING SETS– SELECT CITY,RATING,COUNT(CID) FROM CUSTOMERS

– GROUP BY GROUPING SETS(CITY,RATING,(CITY,RATING),())

– ORDER BY CITY;

• Note: Compute the subtotals for every member in the GROUPING SETS. () indicates that an overall total is desired.

Page 18: Decision Support and Data Warehouse. Decision supports Systems Components Data management function –Data warehouse Model management function –Analytical.

ResultsCITY Rating COUNT(CID)-------------------- - ---------- ------------------CHICAGO A 1CHICAGO B 2CHICAGO 3LOS ANGELES A 1LOS ANGELES C 1LOS ANGELES 2SAN FRANCISCO A 2SAN FRANCISCO B 1SAN FRANCISCO 3 A 4 8

CITY R COUNT(CID)-------------------- - ---------- B 3 C 1

Page 19: Decision Support and Data Warehouse. Decision supports Systems Components Data management function –Data warehouse Model management function –Analytical.

SQL CUBE

• Perform aggregations for all possible combinations of columns indicated.– SELECT CITY,RATING,COUNT(CID) FROM CUSTOMERS

– GROUP BY CUBE(CITY,RATING)

– ORDER BY CITY, RATING;

Page 20: Decision Support and Data Warehouse. Decision supports Systems Components Data management function –Data warehouse Model management function –Analytical.

ResultsCITY Rating COUNT(CID)-------------------- - ------- ----------CHICAGO A 1CHICAGO B 2CHICAGO 3LOS ANGELES A 1LOS ANGELES C 1LOS ANGELES 2SAN FRANCISCO A 2SAN FRANCISCO B 1SAN FRANCISCO 3 A 4 B 3

CITY R COUNT(CID)-------------------- - ---------- C 1 8

Page 21: Decision Support and Data Warehouse. Decision supports Systems Components Data management function –Data warehouse Model management function –Analytical.

SQL ROLLUP

• The ROLLUP extension causes cumulative subtotals to be calculated for the columns indicated. If multiple columns are indicated, subtotals are performed for each of the columns except the far-right column.– SELECT CITY,RATING,COUNT(CID) FROM CUSTOMERS– GROUP BY ROLLUP(CITY,RATING)– ORDER BY CITY, RATING;

Page 22: Decision Support and Data Warehouse. Decision supports Systems Components Data management function –Data warehouse Model management function –Analytical.

Results

CITY Rating COUNT(CID)-------------------- - ----------CHICAGO A 1CHICAGO B 2CHICAGO 3LOS ANGELES A 1LOS ANGELES C 1LOS ANGELES 2SAN FRANCISCO A 2SAN FRANCISCO B 1SAN FRANCISCO 3 8

Page 23: Decision Support and Data Warehouse. Decision supports Systems Components Data management function –Data warehouse Model management function –Analytical.

Need for Data Warehousing• Integrated, company-wide view of high-quality

information (from disparate databases)• Separation of operational and informational systems

and data (for improved performance)