final_columns = ['colA', 'colB', 'colC', 'colD', 'colE']

try:
    sdf = sqlContext.table('test_table')
except:
    print("test_table is empty")
    mySchema = StructType([ StructField("colA", StringType(), True),
                            StructField("colB", StringType(), True),
                            StructField("colC", StringType(), True),
                            StructField("colD", StringType(), True),
                            StructField("colE", DoubleType(), True) ])
    sdf = sqlContext.createDataFrame(spark.sparkContext.emptyRDD(),schema=mySchema)

sdf = sdf.select(final_columns)