Added Onboarded Cities

Author: thecoddiwompler

Onboarded Cities/READme.md

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+# Onboarded Cities
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+
+---
+## 🛠️ Problem Statement
+
+  <b>Table Name : business_city</b>
+
+|  Column Name  |Type |
+| ------------- | ------------- |
+| business_date  | date  |
+| city_id  | int  |
+
+</br>
+
+The table contains two columns business_date and city_id. city_id is the ID of the city which has been onboarded for the business. Note that there could be multiple instances of onboarding of a particular city.
+
+Write a SQL query to find the Unique number of cities onboarded for the business for the first time for each year.
+
+Return the result table in the order of business_year.
+
+The query result format is in the following example. 
+
+ <details>
+<summary>
+Input
+</summary>
+</br>
+
+<b> Table Name: business_city </b></br>
+
+| business_year | city_id |
+|---------------|---------|
+| 2020-01-02    | 3       |
+| 2020-07-01    | 7       |
+| 2021-01-01    | 3       |
+| 2021-02-03    | 19      |
+| 2022-12-01    | 3       |
+| 2022-12-15    | 3       |
+| 2022-02-28    | 12      |
+
+
+
+</details>
+
+<details>
+<summary>
+Output
+</summary>
+</br>
+
+| business_city         | no_of_onboarded_cities_for_the_first_time  |
+|-------------------------|----------|
+| 2020 | 2 |
+| 2021  |   1   |
+| 2022 | 1 |
+
+
+</details>
+
+---

Onboarded Cities/schema.sql

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+CREATE TABLE business_city (business_date date, city_id int);
+
+INSERT INTO
+    business_city
+VALUES
+    (cast('2020-01-02' AS date), 3),
+    (cast('2020-07-01' AS date), 7),
+    (cast('2021-01-01' AS date), 3),
+    (cast('2021-02-03' AS date), 19),
+    (cast('2022-12-01' AS date), 3),
+    (cast('2022-12-15' AS date), 3),
+    (cast('2022-02-28' AS date), 12);
+
+COMMIT;

Onboarded Cities/solution.sql

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+WITH cte AS (
+    SELECT
+        TO_CHAR(business_date, 'YYYY') business_year,
+        city_id,
+        ROW_NUMBER() OVER(
+            PARTITION by city_id
+            ORDER BY
+                to_char(business_date, 'YYYY')
+        ) rn
+    FROM
+        business_city
+)
+SELECT
+    business_year,
+    COUNT(*) no_of_onboarded_cities_for_the_first_time
+FROM
+    cte
+WHERE
+    rn = 1
+GROUP BY
+    1

iqsql.md

@@ -9,4 +9,5 @@
 9. Manager with at least 5 direct reportees
 10. Mismatched IDs
 11. Odd and Even Measurements
-12. Qualifying Criteria
+12. Onboarded Cities
+13. Qualifying Criteria