Spark sql with JDBC
  ./sbin/start-master.sh   you will get master is running on a hostname and a port number. copy that and put in blow command   ./bin/spark-shell --driver-memory 4G --master spark://master-host:7077 --executor-memory 8G --executor-cores 1 --num-executors 3   import java.util.Properties  val connectionProperties = new Properties()  connectionProperties.put("user", "actualUsername")  connectionProperties.put("password", "actualPassword")  val jdbcUrl = "jdbc:mysql://hostname/dbname"   val sqlquery = "(select * from t1 limit 10)tmp"   val df = spark.read.jdbc(url=jdbcUrl, table=sqlquery, properties=connectionProperties)   df.show     for ms sql: https://docs.microsoft.com/en-us/sql/connect/jdbc/building-the-connection-url?view=sql-server-2017   
