val jdbcDF = spark.read.format("jdbc").option("url", "jdbc:MySQL://hadoop000:3306").option("dbtable", "hive.dept").option("user", "root").option("password", "123456").load()
jdbcDF.createOrReplaceTempView("dept")
val hiveDF = sql("SELECT * FROM emp")
val sqlDF = sql("SELECT * FROM emp e JOIN dept d ON e.deptno = d.deptno").show

sqlDF.write.format("json").save("file:///empJoinDept.json")

网页标题：SparkSQL读取MySQL的dept和hive的emp表，做join和分组查询，后写到json
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