task: #585 & SQL-50 plan completed

Author: Ivanbyone

README.md

@@ -83,6 +83,7 @@ Have a good contributing!
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     - [570. Managers with at Least 5 Direct Reports](./leetcode/medium/570.%20Managers%20with%20at%20Least%205%20Direct%20Reports.sql)
+    - [585. Investments in 2016](./leetcode/medium/585.%20Investments%20in%202016.sql)
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leetcode/medium/585. Investments in 2016.sql

@@ -0,0 +1,45 @@
+/*
+Question 585. Investments in 2016
+Link: https://leetcode.com/problems/investments-in-2016/description/?envType=study-plan-v2&envId=top-sql-50
+
+Table: Insurance
+
++-------------+-------+
+| Column Name | Type  |
++-------------+-------+
+| pid         | int   |
+| tiv_2015    | float |
+| tiv_2016    | float |
+| lat         | float |
+| lon         | float |
++-------------+-------+
+pid is the primary key (column with unique values) for this table.
+Each row of this table contains information about one policy where:
+pid is the policyholder's policy ID.
+tiv_2015 is the total investment value in 2015 and tiv_2016 is the total investment value in 2016.
+lat is the latitude of the policy holder's city. It's guaranteed that lat is not NULL.
+lon is the longitude of the policy holder's city. It's guaranteed that lon is not NULL.
+ 
+
+Write a solution to report the sum of all total investment values in 2016 tiv_2016, for all policyholders who:
+
+have the same tiv_2015 value as one or more other policyholders, and
+are not located in the same city as any other policyholder (i.e., the (lat, lon) attribute pairs must be unique).
+Round tiv_2016 to two decimal places.
+*/
+
+SELECT ROUND(SUM(i.tiv_2016)::numeric, 2) AS tiv_2016
+FROM Insurance AS i
+WHERE (i.lat, i.lon) IN (
+    SELECT 
+        i1.lat, 
+        i1.lon 
+    FROM Insurance AS i1
+    GROUP BY i1.lat, i1.lon
+    HAVING COUNT(1) = 1
+) AND i.tiv_2015 IN (
+    SELECT i2.tiv_2015
+    FROM Insurance AS i2
+    GROUP BY i2.tiv_2015
+    HAVING COUNT(1) > 1
+)