Get Started Free
Tutorial

How to compute the difference between two columns with ksqlDB

ksqlDB
‹ Back to Tutorials

How to compute the difference between two columns with ksqlDB

This tutorial demonstrates how to calculate the difference between two columns.

Setup

The first thing we do is to create a stream named PURCHASE_STREAM

CREATE STREAM PURCHASE_STREAM (
                  ID VARCHAR,
                  PREVIOUS_PURCHASE DOUBLE,
                  CURRENT_PURCHASE DOUBLE,
                  TXN_TS VARCHAR,
                  FIRST_NAME VARCHAR,
                  LAST_NAME  VARCHAR)

 WITH (KAFKA_TOPIC='customer_purchases',
       VALUE_FORMAT='JSON',
       PARTITIONS=1);

Calculate the difference between two columns

Now create a query to determine the difference between two columns:

CREATE STREAM PURCHASE_HISTORY_STREAM AS
  SELECT FIRST_NAME,
         LAST_NAME,
         CURRENT_PURCHASE - PREVIOUS_PURCHASE as PURCHASE_DIFF
FROM PURCHASE_STREAM;