SPARK SQL - case when then

Question

I'm new to SPARK-SQL. Is there an equivalent to "CASE WHEN 'CONDITION' THEN 0 ELSE 1 END" in SPARK SQL ?

select case when 1=1 then 1 else 0 end from table

Thanks Sridhar

question from:https://stackoverflow.com/questions/25157451/spark-sql-case-when-then

Answer 1

Before Spark 1.2.0

The supported syntax (which I just tried out on Spark 1.0.2) seems to be

SELECT IF(1=1, 1, 0) FROM table

This recent thread http://apache-spark-user-list.1001560.n3.nabble.com/Supported-SQL-syntax-in-Spark-SQL-td9538.html links to the SQL parser source, which may or may not help depending on your comfort with Scala. At the very least the list of keywords starting (at time of writing) on line 70 should help.

Here's the direct link to the source for convenience: https://github.com/apache/spark/blob/master/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/SqlParser.scala.

Update for Spark 1.2.0 and beyond

As of Spark 1.2.0, the more traditional syntax is supported, in response to SPARK-3813: search for "CASE WHEN" in the test source. For example:

SELECT CASE WHEN key = 1 THEN 1 ELSE 2 END FROM testData

Update for most recent place to figure out syntax from the SQL Parser

The parser source can now be found here.

Update for more complex examples

In response to a question below, the modern syntax supports complex Boolean conditions.

SELECT
    CASE WHEN id = 1 OR id = 2 THEN "OneOrTwo" ELSE "NotOneOrTwo" END AS IdRedux
FROM customer

You can involve multiple columns in the condition.

SELECT
    CASE WHEN id = 1 OR state = 'MA' 
         THEN "OneOrMA" 
         ELSE "NotOneOrMA" END AS IdRedux
FROM customer

You can also nest CASE WHEN THEN expression.

SELECT
    CASE WHEN id = 1 
         THEN "OneOrMA"
         ELSE
             CASE WHEN state = 'MA' THEN "OneOrMA" ELSE "NotOneOrMA" END
    END AS IdRedux
FROM customer