sparkContext是针对RDD的读写，后面DataFrame用sparkSession
转换先得变成Row,Row是数据框的行对象，然后创建dataframe就行了
如果要查询,通过spark.sql，必须得注册成临时表才行
from pyspark.sql import Row
people = spark.sparkContext.textFile(“file:///文件目录”).map(lambda x:x.split(",")).map(lambda p:Row(name=p[0],age=int(p[1])))
schemap=spark.createDataFrame(people)
schemap.createOrReplace(TempView(“people”))#注意这里对象引用加引号了
peopleDF=spark.sql(“select name,age from people where age>20”)
peopleRDD=peopleDF.rdd.map(lambda p:“name:”+p.name+","+“age:”+str(p.age))
peopleRDD.foreach(print)
