Updated tutorial

Author: Stefan Azaric

articles/synapse-analytics/sql/media/tutorial-data-analyst/plot-chart-public-holidays.png

@@ -135,41 +135,50 @@ From the plot chart, you can see there's a weekly pattern, with Saturdays as the
 Next, let's see if the drop in rides correlates with public holidays. We can see if there is a correlation by joining the NYC Taxi rides dataset with the Public Holidays dataset:
 
 ```sql
-WITH taxi_rides AS
-(
-    SELECT
-        CAST([tpepPickupDateTime] AS DATE) AS [current_day],
-        COUNT(*) as rides_per_day
-    FROM  
-        OPENROWSET(
-            BULK 'https://azureopendatastorage.blob.core.windows.net/nyctlc/yellow/puYear=*/puMonth=*/*.parquet',
-            FORMAT='PARQUET'
-        ) AS [nyc]
-    WHERE nyc.filepath(1) = '2016'
-    GROUP BY CAST([tpepPickupDateTime] AS DATE)
+WITH taxi_rides AS (
+SELECT
+    CAST([tpepPickupDateTime] AS DATE) AS [current_day],
+    COUNT(*) as rides_per_day
+FROM
+    OPENROWSET(
+        BULK 'https://azureopendatastorage.blob.core.windows.net/nyctlc/yellow/puYear=*/puMonth=*/*.parquet',
+        FORMAT='PARQUET'
+    ) AS [nyc]
+WHERE nyc.filepath(1) = '2016'
+GROUP BY CAST([tpepPickupDateTime] AS DATE)
 ),
-public_holidays AS
-(
-    SELECT
-        holidayname as holiday,
-        date
-    FROM
-        OPENROWSET(
-            BULK 'https://azureopendatastorage.blob.core.windows.net/holidaydatacontainer/Processed/*.parquet',
-            FORMAT='PARQUET'
-        ) AS [holidays]
-    WHERE countryorregion = 'United States' AND YEAR(date) = 2016
-)
+public_holidays AS (
+SELECT
+    holidayname as holiday,
+    date
+FROM
+    OPENROWSET(
+        BULK 'https://azureopendatastorage.blob.core.windows.net/holidaydatacontainer/Processed/*.parquet',
+        FORMAT='PARQUET'
+    ) AS [holidays]
+WHERE countryorregion = 'United States' AND YEAR(date) = 2016
+),
+joined_data AS (
 SELECT
-*
+    *
 FROM taxi_rides t
 LEFT OUTER JOIN public_holidays p on t.current_day = p.date
+)
+
+SELECT 
+    *,
+    holiday_rides = 
+    CASE   
+      WHEN holiday is null THEN 0   
+      WHEN holiday is not null THEN rides_per_day
+    END   
+FROM joined_data
 ORDER BY current_day ASC
 ```
 
 ![NYC Taxi rides and Public Holidays datasets result visualization](./media/tutorial-data-analyst/rides-public-holidays.png)
 
-This time, we want to highlight the number of taxi rides during public holidays. For that purpose, we choose **none** for the **Category** column and **rides_per_day** and **holiday** as the **Legend (series)** columns.
+This time, we want to highlight the number of taxi rides during public holidays. For that purpose, we choose **current_day** for the **Category** column and **rides_per_day** and **holiday_rides** as the **Legend (series)** columns.
 
 ![Number of taxi rides during public holidays plot chart](./media/tutorial-data-analyst/plot-chart-public-holidays.png)