[FEATURE REQUEST]: Add more Data Frame examples #600
Description
Is your feature request related to a problem? Please describe.
Some common Data frame transforms are missing from the Basic Batch Spark SQL examples examples/Microsoft.Spark.CSharp.Examples/Sql/Batch/Basic.cs. Transformations such as unions, addition/removal of columns etc.
Describe the solution you'd like
I'd like to add more examples of how to create a union between two data frames. Also show how to add/rename/drop columns.
Additional context
I think its important to demonstrate how to use existing spark features in dotnet.