SQL6: Problem Solutions RN32MAY2025DS

CustomersWithStrictlyIncreasingPurchases.sql

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+WITH cte AS (
+    SELECT  customer_id,
+            YEAR(order_date) AS year,
+            SUM(price) AS price
+    FROM orders
+    GROUP BY 1,2
+    ORDER BY 1,2
+)
+SELECT  DISTINCT c1.customer_id
+FROM cte c1
+LEFT JOIN cte c2
+ON (c1.customer_id = c2.customer_id
+AND c1.year + 1 = c2.year
+AND c2.price > c1.price)
+GROUP BY 1
+HAVING COUNT(c1.customer_id) - COUNT(c2.customer_id) = 1;

ShortestDistanceInaPlane.sql

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+-- Solution for Leetcode problem ShortestDistanceInaPlane
+SELECT  MIN(ROUND(SQRT(POW(p1.x - p2.x, 2) + POW(p1.y - p2.y, 2)), 2)) AS shortest
+FROM point2d p1
+JOIN point2d p2
+ON p1.x < p2.x OR p1.y < p2.y
+/*we can also use the following*/
+-- ON (p1.x,p1.y) < (p2.x,p2.y)
+;

combine_two_tables

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+SELECT  p.firstname,
+        p.lastname,
+        a.city,
+        a.state
+FROM person p
+LEFT JOIN address a
+ON p.personid = a.personid;

game_analysis_2

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+-- Method 1
+WITH cte AS (
+    SELECT  player_id,
+            MIN(event_date) AS first_login
+    FROM activity
+    GROUP BY player_id
+)
+SELECT  a.player_id,
+        a.device_id
+FROM activity a
+JOIN cte c
+ON a.player_id = c.player_id AND a.event_date = c.first_login;
+
+-- Method 2
+SELECT  DISTINCT player_id,
+        FIRST_VALUE(device_id) OVER(PARTITION BY player_id ORDER BY event_date RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) device_id
+FROM activity;
+
+-- Method 3
+SELECT  player_id,
+        device_id
+FROM (
+    SELECT  player_id,
+            device_id,
+            DENSE_RANK() OVER(PARTITION BY player_id ORDER BY event_date) rnk
+    FROM activity
+)a
+WHERE rnk = 1;

game_play_analysis_3

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+-- Method 1
+SELECT  player_id,
+        event_date,
+        SUM(games_played) OVER(PARTITION BY player_id ORDER BY event_date) AS games_played_so_far
+FROM activity;
+
+-- Method 2
+SELECT  a1.player_id,
+        a1.event_date,
+        (SELECT SUM(a2.games_played)
+        FROM activity a2
+        WHERE a1.player_id = a2.player_id
+        AND a2.event_date <= a1.event_date) AS games_played_so_far
+FROm activity a1;