add comments and rename file

Author: Adi

getting-started/SparkJDBCtoDBs.ipynb getting-started/spark-jdbc.ipynbgetting-started/SparkJDBCtoDBs.ipynb renamed to getting-started/spark-jdbc.ipynb

@@ -106,7 +106,8 @@
     "from pyspark.sql import SparkSession\n",
     "\n",
     "# METHOD I:\n",
-    "#   Update Spark configurations of the following two extraClassPath prior to initiating a Spark session:\n",
+    "#   Update Spark configurations of the following two extraClassPath with the JDBC driver location\n",
+    "#   prior to initiating a Spark session:\n",
     "#      spark.driver.extraClassPath\n",
     "#      spark.executor.extraClassPath\n",
     "#\n",
@@ -122,12 +123,16 @@
     "\n",
     "\"\"\"\n",
     "# METHOD II:\n",
-    "#   Use \"PYSPARK_SUBMIT_ARGS\" with \"--packages\" option.\n",
+    "#   Use \"PYSPARK_SUBMIT_ARGS\" with \"--packages\" option.  (The preferred way)\n",
     "# \n",
+    "# Usage:\n",
+    "# os.environ[\"PYSPARK_SUBMIT_ARGS\"] = \"--packages dialect:dialect-specific-jdbc-connector:version# pyspark-shell\"\n",
+    "#\n",
     "# NOTE:\n",
     "# If you don't connnect to mysql, replace the mysql's connector by the other database's JDBC connector \n",
     "# in the following line.\n",
     "\"\"\"\n",
+    "# Set PYSPARK_SUBMIT_ARGS\n",
     "#os.environ[\"PYSPARK_SUBMIT_ARGS\"] = \"--packages mysql:mysql-connector-java:5.1.39 pyspark-shell\"\n",
     "\n",
     "\"\"\"\n",
@@ -137,8 +142,7 @@
     "#      spark.executor.extraClassPath\n",
     "\"\"\"  \n",
     "# Initiate a Spark Session\n",
-    "#spark = SparkSession.builder.\\\n",
-    "#    appName(\"Spark JDBC to Databases - ipynb\").getOrCreate()"
+    "#spark = SparkSession.builder.appName(\"Spark JDBC to Databases - ipynb\").getOrCreate()"
    ]
   },
   {