Added Trip Details

Author: thecoddiwompler

Trip Details/README.md

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+# Trip Details
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+
+---
+
+## 🛠️ Problem Statement
+
+  <b>Table Name : travel_data</b>
+
+|  Column Name  |Type |
+| ------------- | ------------- |
+| customer   | varchar(20)     |
+| start_loc          | varchar(50) |
+| end_loc    | varchar(50)    |
+
+This table contains data about passengers traveling between various cities.  </br>
+</br>
+
+You are given the travel data for each customer in no particular order. <br>
+Write a SQL to find the start location and end location of the customer and total number of locations covered by them.</br>
+</br>
+
+The query result format is in the following example:  
+
+ <details>
+<summary>
+Input
+</summary>
+ </br>
+
+ <b>Table Name: travel_data</b>
+
+| customer | start_loc  | end_loc    |
+|----------|------------|------------|
+| c1       | New York   | Lima       |
+| c1       | London     | New York   |
+| c1       | Lima       | Sao Paulo  |
+| c1       | Sao Paulo  | New Delhi  |
+| c2       | Mumbai     | Hyderabad  |
+| c2       | Surat      | Pune       |
+| c2       | Hyderabad  | Surat      |
+| c3       | Kochi      | Kurnool    |
+| c3       | Lucknow    | Agra       |
+| c3       | Agra       | Jaipur     |
+| c3       | Jaipur     | Kochi      |
+
+
+
+</details>
+
+<details>
+<summary>
+Output
+</summary>
+</br>
+  
+| customer | start_loc | end_loc   | place_visited |
+|----------|-----------|-----------|---------------|
+| c1       | London  | New Delhi | 5           |
+| c2       | Mumbai    | Pune      | 4             |
+| c3       | Lucknow     | Kurnool     | 5            |
+
+
+</details>
+
+---

Trip Details/schema.sql

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+CREATE TABLE travel_data (
+    customer VARCHAR(10),
+    start_loc VARCHAR(50),
+    end_loc VARCHAR(50)
+);
+
+INSERT INTO
+    travel_data (customer, start_loc, end_loc)
+VALUES
+    ('c1', 'New York', 'Lima'),
+    ('c1', 'London', 'New York'),
+    ('c1', 'Lima', 'Sao Paulo'),
+    ('c1', 'Sao Paulo', 'New Delhi'),
+    ('c2', 'Mumbai', 'Hyderabad'),
+    ('c2', 'Surat', 'Pune'),
+    ('c2', 'Hyderabad', 'Surat'),
+    ('c3', 'Kochi', 'Kurnool'),
+    ('c3', 'Lucknow', 'Agra'),
+    ('c3', 'Agra', 'Jaipur'),
+    ('c3', 'Jaipur', 'Kochi');
+
+COMMIT;

Trip Details/solution.sql

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+WITH cte AS (
+    SELECT
+        a.customer,
+        a.start_loc,
+        a.end_loc,
+        b.end_loc prev_end_loc,
+        c.start_loc next_start_loc
+    FROM
+        travel_data a
+        LEFT OUTER JOIN travel_data b ON a.start_loc = b.end_loc
+        LEFT OUTER JOIN travel_data c ON a.end_loc = c.start_loc
+),
+start_location AS (
+    SELECT
+        customer,
+        start_loc
+    FROM
+        cte
+    WHERE
+        prev_end_loc IS NULL
+),
+end_location AS (
+    SELECT
+        customer,
+        end_loc
+    FROM
+        cte
+    WHERE
+        next_start_loc IS NULL
+),
+counter AS (
+    SELECT
+        customer,
+        COUNT(*) + 1 place_visited
+    FROM
+        cte
+    GROUP BY
+        customer
+)
+SELECT
+    a.customer,
+    a.start_loc,
+    b.end_loc,
+    c.place_visited
+FROM
+    start_location a
+    INNER JOIN end_location b ON a.customer = b.customer
+    INNER JOIN counter c ON a.customer = c.customer;