Create 1384-total-sales-amount-by-year.sql

Author: everthis

1384-total-sales-amount-by-year.sql

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+# Write your MySQL query statement below
+SELECT
+    b.product_id,
+    a.product_name,
+    a.yr AS report_year,
+    CASE 
+        WHEN YEAR(b.period_start)=YEAR(b.period_end) AND a.yr=YEAR(b.period_start) THEN DATEDIFF(b.period_end,b.period_start)+1
+        WHEN a.yr=YEAR(b.period_start) THEN DATEDIFF(DATE_FORMAT(b.period_start,'%Y-12-31'),b.period_start)+1
+        WHEN a.yr=YEAR(b.period_end) THEN DAYOFYEAR(b.period_end) 
+        WHEN a.yr>YEAR(b.period_start) AND a.yr<YEAR(b.period_end) THEN 365
+        ELSE 0
+    END * average_daily_sales AS total_amount
+FROM
+    (SELECT product_id,product_name,'2018' AS yr FROM Product
+    UNION
+    SELECT product_id,product_name,'2019' AS yr FROM Product
+    UNION
+    SELECT product_id,product_name,'2020' AS yr FROM Product) a
+    JOIN 
+    Sales b
+    ON a.product_id=b.product_id  
+HAVING total_amount > 0
+ORDER BY b.product_id,a.yr;