Using CASE and WHENΒΆ
At times we might have to select values from multiple columns conditionally.
Let us start spark context for this Notebook so that we can execute the code provided. You can sign up for our 10 node state of the art cluster/labs to learn Spark SQL using our unique integrated LMS.
val username = System.getProperty("user.name")
import org.apache.spark.sql.SparkSession
val username = System.getProperty("user.name")
val spark = SparkSession.
builder.
config("spark.ui.port", "0").
config("spark.sql.warehouse.dir", s"/user/${username}/warehouse").
enableHiveSupport.
appName(s"${username} | Spark SQL - Predefined Functions").
master("yarn").
getOrCreate
If you are going to use CLIs, you can use Spark SQL using one of the 3 approaches.
Using Spark SQL
spark2-sql \
--master yarn \
--conf spark.ui.port=0 \
--conf spark.sql.warehouse.dir=/user/${USER}/warehouse
Using Scala
spark2-shell \
--master yarn \
--conf spark.ui.port=0 \
--conf spark.sql.warehouse.dir=/user/${USER}/warehouse
Using Pyspark
pyspark2 \
--master yarn \
--conf spark.ui.port=0 \
--conf spark.sql.warehouse.dir=/user/${USER}/warehouse
We can use
CASE
andWHEN
for that.Let us implement this conditional logic to come up with derived order_status.
If order_status is COMPLETE or CLOSED, set COMPLETED
If order_status have PENDING in it, then we will say PENDING
If order_status have PROCESSING or PAYMENT_REVIEW in it, then we will say PENDING
We will set all others as OTHER
We can also have
ELSE
as part ofCASE
andWHEN
.
%%sql
USE itversity_retail
%%sql
SHOW tables
%%sql
SELECT DISTINCT order_status FROM orders LIMIT 10
%%sql
SELECT o.*,
CASE WHEN order_status IN ('COMPLETE', 'CLOSED') THEN 'COMPLETED'
END AS updated_order_status
FROM orders o
LIMIT 10
%%sql
SELECT o.*,
CASE WHEN order_status IN ('COMPLETE', 'CLOSED') THEN 'COMPLETED'
ELSE order_status
END AS updated_order_status
FROM orders o
LIMIT 10
%%sql
SELECT o.*,
CASE
WHEN order_status IN ('COMPLETE', 'CLOSED') THEN 'COMPLETED'
WHEN order_status LIKE '%PENDING%' THEN 'PENDING'
ELSE 'OTHER'
END AS updated_order_status
FROM orders o
LIMIT 10
%%sql
SELECT o.*,
CASE
WHEN order_status IN ('COMPLETE', 'CLOSED') THEN 'COMPLETED'
WHEN order_status LIKE '%PENDING%' OR order_status IN ('PROCESSING', 'PAYMENT_REVIEW')
THEN 'PENDING'
ELSE 'OTHER'
END AS updated_order_status
FROM orders o
LIMIT 10
%%sql
SELECT DISTINCT order_status,
CASE
WHEN order_status IN ('COMPLETE', 'CLOSED') THEN 'COMPLETED'
WHEN order_status LIKE '%PENDING%' OR order_status IN ('PROCESSING', 'PAYMENT_REVIEW')
THEN 'PENDING'
ELSE 'OTHER'
END AS updated_order_status
FROM orders
ORDER BY updated_order_status