In this article, we will learn how to implement DENSE RANK operation in SAP Data Services.

Implementation

Let us take the Employee table as Source. We want to RANK all the employees based on their salary. So the Employee with the highest salary will get first rank and the employee with lowest salary will get the last rank. Now in the event when many employees have the same salary then they basically share the same rank. But in case of dense ranking the immediate next record will get the next consecutive rank. There will be no gap in RANKS generated.

1. First we create a Batch Job, say Job_Dense_Rank_Generation. Within the Job we create a Data Flow, say Df_Dense_Rank_Generation.

2. Next we create a New Custom Function from the Local Object Library. Lets name it CF_DENSE_RANK_GENERATION.

Custom Function

Within the Custom Function Smart Editor, we define the Parameters and Variables as below:

Param/VariableNameDatatypeType
ParameterReturnint
Parameter$PREV_SALdecimal(7,2)Input
Parameter$CURR_SALdecimal(7,2)Input
Variable$HOLD_RANKint

Custom Function Definition

The Return Parameter Data type is int.

3. Next we define the Custom Function CF_DENSE_RANK_GENERATION as below and Validate the same.

if( $PREV_SAL IS NULL )
begin
  $HOLD_RANK = 1;
  Return $HOLD_RANK;
end

else if( $PREV_SAL = $CURR_SAL )
begin
  Return $HOLD_RANK;
end

else
begin
  $HOLD_RANK = $HOLD_RANK + 1;
  Return $HOLD_RANK;
end

4. Lets go back and design the Dataflow. First of all we take the EMP table, from the Local Object Library as Source.

Data flow

5. Next we place a Query transform, say QRY_SORT_SAL_DESC to sort the employee data based salary in descending order. First we select all the columns from the Schema In of the Query transform and Map to Output. Next on the ORDER BY tab, select the EMP.SAL column of the Schema In and Sort Type as Descending

Query- Sort

6. Next we place another Query transform, say QRY_SET_PARAM to set the Parameter values that will passed as arguments to the Custom Function to get the Ranking. First we select all the columns from the Schema In of the Query transform and Map to Output. Next we create a New Output Column, say PREV_SAL with Data type as decimal(7,2) to capture the previous row value of salary and define the Mapping as below:

previous_row_value( QRY_SORT_SAL_DESC.SAL )

Query- Set Parameter

7. Next we place another Query transform, say QRY_GEN_RANK to call the Custom Function with the input parameters that we have already designed in the previous transform. First we select all the columns except PREV_SAL from the Schema In of the Query transform and Map to Output. Call the Function with the Input Parameters as below. This function will eventually return the Rank for each record based on the salary.

Create a New Function Call in Schema Out of the Query transform. Choose the Custom Functions from the Function categories and select the Function name CF_DENSE_RANK_GENERATION.

Next we Define Input Parameters. We specify the inputs as below:

$PREV_SAL = QRY_SET_PARAM.PREV_SAL
$CURR_SAL = QRY_SET_PARAM.SAL

Function Input Parameters

Select the Return column as the Output Parameter.

Query- Rank

8. Finally we place a Template Table as Target in the Target Datastore.

Data Preview


Have a question on this subject?

Ask questions to our expert community members and clear your doubts. Asking question or engaging in technical discussion is both easy and rewarding.

Are you on Twitter?

Start following us. This way we will always keep you updated with what's happening in Data Analytics community. We won't spam you. Promise.

  • How to implement SCD Type 2 using History Preserve Transform in Data Services

    This tutorial teaches you how to use the "History Preserving Transform" in SAP Data Services (BODS) by demonstrating a practical use of this transform for the implementation of SCD Type 2. We have also provided hands-on video below so that you can...

  • GROUP RANK in Data Services

    In this article, we will learn how to implement RANK and DENSE RANK operations on GROUP in SAP Data Services.

  • How to handle multiple input file in SAP Data Services

    In this tutorial, we will learn how we can use a single data flow to process multiple input files of same structure using SAP Data Services. Like before, we have included one hands-on video with the tutorial to help you see the technique in action

  • Auditing in SAP Data Services

    A proper data reconciliation process must be in place in any data Extraction-Transformation-Load (ETL) process. A successful reconciliation process should only indicate whether or not the data is correct. But data reconciliation is not easy....

  • One Stop to SAP BODI/BODS

    BODI Business Objects Data Integrator or BODS Business Objects Data Services is a GUI workspace that allows to create jobs that extracts data from heterogeneous sources, transforms that data using built-in transforms and functions to meet business...

  • How to implement SCD Type 3 in Data Services

    In this tutorial we will learn how to implement Slowly Changing Dimension of Type 3 using SAP Data Services. SCD type 3 design is used to store partial history. Here we are only interested to maintain the "current value" and "previous value" of an...

  • Top 50 SAP Business Objects Data Services (BODS) Interview Questions with Answers

    Learn the answers of some critical questions commonly asked during SAP BO Data Services interview.

  • SAP BODS Transforms

    This article deals with the various types of transformations available in SAP BODS. Transformations are in-built, optional objects used in dataflow to transform source data to desired output dataset objects available in Local Object Library under...

  • Real Time Jobs in Data Services

    SAP Data Services provides Realtime Data Integration features. Data Services can generate realtime event messages and can also listen to input XML messages. Real Time Job means, some message with content will trigger the Job or Dataflow processing. A RealTime...

  • Fools Guide to BODS - Introductory Tutorial

    This article is a guide to the readers who are totally ignorant about the tool SAP Business Objects Data Services. It is presented in a very simple way so that readers would be familiar with common terms, terminologies and would be able to run...