SQL3 COMPLETED

README.md

@@ -2,8 +2,57 @@
 
 1 Problem 1 : Consecutive Numbers	(https://leetcode.com/problems/consecutive-numbers/)
 
+Solution:
+Select Distinct l3.num As ConsecutiveNums  from logs l1, logs l2, logs l3
+where l1.id = l2.id - 1
+AND l2. id = l3.id - 1
+AND l1.num = l2.num AND l2.num = l3.num
+
+
 2 Problem 2 :Number of Passengers in Each Bus 	(	https://leetcode.com/problems/the-number-of-passengers-in-each-bus-i/ )
 
+Solution:
+with cte as (SELECT 
+    p.passenger_id, 
+    p.arrival_time, 
+    MIN(b.arrival_time) AS bTime
+FROM Passengers p
+JOIN Buses b 
+    ON p.arrival_time <= b.arrival_time 
+GROUP BY p.passenger_id
+)
+
+Select b.bus_id, count(c.btime) As 'passengers_cnt'
+FROM buses b 
+Left join cte c
+on b.arrival_time = c.btime 
+Group by b.bus_id
+order by b.bus_id
 3 Problem 3 :User Activity		(https://leetcode.com/problems/user-activity-for-the-past-30-days-i/ )
 
+Solution:
+Select activity_date AS "day", 
+Count(DISTINCT user_id) AS "active_users"
+FROM Activity
+WHERE DATEDIFF ('2019-07-27' , activity_date) >=0
+AND DATEDIFF ('2019-07-27' , activity_date) <= 29
+GROUP BY activity_date 
+
 4 Problem 4 :Dynamic Pivoting of a Table	(	https://leetcode.com/problems/dynamic-pivoting-of-a-table/ )
+
+Solution:
+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;
+
+    SET @sql = CONCAT('Select product_id,', @sql, ' from Products group by product_id');
+
+    prepare statement from @sql;
+    execute statement;
+    deallocate prepare statement;
+END