Share HDInsight SPARK SQL Table saveAsTable does not work

I want to show the data from HDInsight SPARK using tableau. I was following this video where they have described how to connect the two systems and expose the data.

currently my script itself is very simple as shown below:

 /* csvFile is an RDD of lists, each list representing a line in the CSV file */
val csvLines = sc.textFile("wasb://mycontainer@mysparkstorage.blob.core.windows.net/*/*/*/mydata__000000.csv")

// Define a schema
case class MyData(Timestamp: String, TimezoneOffset: String, SystemGuid: String, TagName: String, NumericValue: Double, StringValue: String)

// Map the values in the .csv file to the schema
val myData = csvLines.map(s => s.split(",")).filter(s => s(0) != "Timestamp").map(
    s => MyData(s(0),
            s(1),
            s(2),
            s(3),
            s(4).toDouble,
            s(5)         
    )
).toDF()
// Register as a temporary table called "processdata"
myData.registerTempTable("test_table")
myData.saveAsTable("test_table") 

unfortunately I run in to the following error

warning: there were 1 deprecation warning(s); re-run with -deprecation for details
org.apache.spark.sql.AnalysisException: Table `test_table` already exists.;
    at org.apache.spark.sql.DataFrameWriter.saveAsTable(DataFrameWriter.scala:209)
    at org.apache.spark.sql.DataFrameWriter.saveAsTable(DataFrameWriter.scala:198)

i have also tried to use the following code to overwrite the table if it exists

   import org.apache.spark.sql.SaveMode
    myData.saveAsTable("test_table", SaveMode.Overwrite) 

but still it gives me same error.

warning: there were 1 deprecation warning(s); re-run with -deprecation for details
java.lang.RuntimeException: Tables created with SQLContext must be TEMPORARY. Use a HiveContext instead.
    at scala.sys.package$.error(package.scala:27)
    at org.apache.spark.sql.execution.SparkStrategies$DDLStrategy$.apply(SparkStrategies.scala:416)
    at org.apache.spark.sql.catalyst.planning.QueryPlanner$$anonfun$1.apply(QueryPlanner.scala:58)
    at org.apache.spark.sql.catalyst.planning.QueryPlanner$$anonfun$1.apply(QueryPlanner.scala:58)
    at scala.collection.Iterator$$anon$13.hasNext(Iterator.scala:371)

Can someone please help me fix this issue?