Update 16-batch-systemfields.ipynb

Added some refs, added a bit to the query.

notebooks/02-ingestion/16-batch-systemfields.ipynb

@@ -5,7 +5,7 @@
    "id": "0cb3b009-ebde-4d56-9d59-a028d66d8309",
    "metadata": {},
    "source": [
-    "# Incorporate system fields into table data\n",
+    "# Incorporate data from source systems into table data\n",
     "<!--\n",
     "  ~ Licensed to the Apache Software Foundation (ASF) under one\n",
     "  ~ or more contributor license agreements.  See the NOTICE file\n",
@@ -27,7 +27,7 @@
     "\n",
     "When doing ingestion from multiple sources, it can be helpful to incorporate specific information from the source of the data.\n",
     "\n",
-    "For example, you may want to parse a file name to use as the primary or a secondary `__time` stamp.\n",
+    "For example, you might parse a source system URI using a [datetime function](https://druid.apache.org/docs/latest/querying/sql-scalar#date-and-time-functions) to use as the primary `__time` stamp.\n",
     "\n",
     "This tutorial demonstrates how to incorporate `systemFields` with batch ingestion to add this information to rows in your table."
    ]
@@ -176,7 +176,7 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "Query the system fields that were ingested to see information about how each file was ingested:"
+    "Run the next cell to run a simple query that shows the results of the ingestion."
    ]
   },
   {
@@ -190,9 +190,10 @@
     "SELECT\n",
     "    \"__file_uri\",\n",
     "    \"__file_path\", \n",
+    "    \"__file_name\",\n",
     "    COUNT(*) AS \"total_file_rows\" \n",
     "FROM \"{table_name}\"\n",
-    "GROUP BY 1,2\n",
+    "GROUP BY 1,2, 3\n",
     "'''\n",
     "\n",
     "druid.display.sql(sql)"