Sql3 solutions

consecutiveNumbers.sql

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+select distinct a.num as ConsecutiveNums from logs a, logs b, logs c
+where (a.num = b.num and a.num = c.num) and 
+(a.id = b.id - 1 and a.id = c.id - 2)

passengersInEachBus.sql

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+
+WITH CTE AS (SELECT P.PASSENGER_ID, MIN(B.ARRIVAL_TIME) AS MIN_BUS_TIME 
+FROM BUSES B INNER JOIN PASSENGERS P 
+ON P.ARRIVAL_TIME <= B.ARRIVAL_TIME 
+GROUP BY P.PASSENGER_ID)
+
+SELECT B.BUS_ID AS BUS_ID, IFNULL(COUNT(P.PASSENGER_ID), 0) PASSENGERS_CNT 
+FROM BUSES B LEFT JOIN CTE P 
+ON MIN_BUS_TIME = B.ARRIVAL_TIME 
+GROUP BY B.BUS_ID ORDER BY 1
+

pivotTable.sql

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+CREATE PROCEDURE PivotProducts()
+BEGIN
+	# Write your MySQL query statement below.
+    set session group_concat_max_len = 1000000;
+    SELECT GROUP_CONCAT(DISTINCT CONCAT ('SUM(IF(STORE = "', 
+    STORE, '", PRICE, NULL)) AS ', STORE )) INTO @SQL FROM PRODUCTS;
+    -- SELECT @SQL;
+    SET @SQL = CONCAT('SELECT product_id, ', @SQL, ' FROM PRODUCTS GROUP BY 1');
+    PREPARE STATEMENT FROM @SQL;
+    EXECUTE STATEMENT;
+    DEALLOCATE PREPARE STATEMENT;
+END

userActivityPast30Days.sql

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+select activity_date as day, count(distinct user_id) as active_users 
+from activity where activity_date >= '2019-06-28' and activity_date <= '2019-07-27' group by activity_date