tailieunhanh - SAS Data Integration Studio 3.3- P41

SAS Data Integration Studio P41:This manual is a companion to the online Help for SAS Data Integration Studio. The Help describes all windows in SAS Data Integration Studio, and it summarizes the main tasks that you can perform with the software. The Help includes examples for all source designer wizards, all target designer wizards, and all transformation templates in the Process Library tree. | 195 Using Slowly Changing Dimensions About Slowly Changing Dimensions 195 SCD Concepts 195 Type 2 SCD Dimensional Model 196 SCD and SAS Data Integration Studio 198 Transformations That Support SCD 198 About the SCD Type 2 Loader Transformation 199 Change Tracking Techniques 199 Selecting Columns for Change Detection 200 Generating Surrogate Keys 201 How Source Data Is Loaded a Dimension Table 202 Example Using Slowly Changing Dimensions 204 Preparation 204 Check Out Existing Metadata That Must Be Updated 205 Create and Populate the Job 205 Add SCD Columns to the Dimension Table 206 Specify the Primary Key for the Dimension Table 207 Specify the Business Key for the SCD Loader 208 Specify the Generated Key for the SCD Loader 209 Set Up Change Tracking in the SCD Loader 210 Set Up Change Detection in the SCD Loader 211 Run the Job and View the Results 212 Check In the Metadata 213 About Slowly Changing Dimensions SCD Concepts A dimension is a category of contextual data or detail data that is implemented in a data model such as a star schema. For example in a star schema a dimension named Customers might associate customer data with transaction identifiers and transaction amounts in a fact table. A dimension table is a table that contains data about a particular dimension in a star schema or a snowflake schema. A primary key connects a dimension table to a related fact table. For example if a dimension table named Customers has a primary key column named Customer ID then a fact table named Customer Sales might specify the Customer ID column as a foreign key. 196 Type 2 SCD Dimensional Model A Chapter 12 A fact table is the central table in a star schema or snowflake schema. A fact table typically contains numerical measurements or amounts and is supplemented by contextual information in dimension tables. For example a fact table might include transaction identifiers and transaction amounts. Dimension tables could add contextual information about customers products .