We use Look up transfermations to implement the SCD to Implement the CDC(Change Data Capture).

The following tasks can be implemented with look up transfermation.

1.Get a Related value.

2.SCD

3.For calculations.

Get a related Value Means tack a simple example when we are using the aggregater transfermation for calculation of avg sal,sum sal by dept wise (in scott table).we get the ans deptno wise.deptno     sumsal       avg sal

10             29000       5555

20             39999         8733

Because emp doesnot containe deptname and location.

This not give u the complete analysis data if we include Department Name and Location wise  sum and avg sal then the information good for analysis.