Databricks Exam Databricks-Certified-Associate-Developer-for-Apache-Spark-3.0 Topic 2 Question 66 Discussion

Correct code block:

transactionsDf.withColumn('transactionDateForm', from_unixtime('transactionDate', 'MMM d (EEEE)'))

The Question: specifically asks about 'adding' a column. In the context of all presented answers, DataFrame.withColumn() is the correct command for this. In theory, DataFrame.select() could

also be

used for this purpose, if all existing columns are selected and a new one is added. DataFrame.withColumnRenamed() is not the appropriate command, since it can only rename existing columns, but

cannot add a new column or change the value of a column.

Once DataFrame.withColumn() is chosen, you can read in the documentation (see below) that the first input argument to the method should be the column name of the new column.

The final difficulty is the date format. The Question: indicates that the date format Apr 26 (Sunday) is desired. The answers give 'MMM d (EEEE)' and 'MM d (EEE)' as options. It can be hard

to

know the details of the date format that is used in Spark. Specifically, knowing the differences between MMM and MM is probably not something you deal with every day. But, there is an easy way

to remember the difference: M (one letter) is usually the shortest form: 4 for April. MM includes padding: 04 for April. MMM (three letters) is the three-letter month abbreviation: Apr for April. And

MMMM is the longest possible form: April. Knowing this four-letter sequence helps you select the correct option here.

More info: pyspark.sql.DataFrame.withColumn --- PySpark 3.1.2 documentation

Static notebook | Dynamic notebook: See test 3, Question: 35 (Databricks import instructions)