Added Odd and Even Measurements

Author: Indrajeet Mishra

Odd and Even Measurements/README.md

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+# [Odd and Even Measurements](https://datalemur.com/questions/odd-even-measurements)
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+
+---
+
+## This problem was asked in Google Interview.
+
+## 🛠️ Problem Statement
+
+  <b>Table Name : Measurements</b>
+
+|  Column Name  |Type |
+| ------------- | ------------- |
+| measurement_id  | INTEGER  |
+| measurement_value  | DECIMAL  |
+| measurement_time | TIMESTAMP |
+
+<b>measurement_id is the primary key of this table.</b>
+</br>
+
+Assume you're given a table with measurement values obtained from a Google sensor over multiple days with measurements taken multiple times within each day.
+
+</br>
+  
+Write a SQL query to calculate the sum of odd-numbered and even-numbered measurements separately for a particular day and display the results in two different columns. Refer to the Example Output below for the desired format.
+
+</br>
+
+Definition:
+<br>
+Within a day, measurements taken at 1st, 3rd, and 5th times are considered odd-numbered measurements, and measurements taken at 2nd, 4th, and 6th times are considered even-numbered measurements.
+
+Return the result table in the order of measurement day.
+
+The query result format is in the following example. 
+
+ <details>
+<summary>
+Input
+</summary>
+</br>
+
+<b> Table Name: Measurements </b></br>
+
+| measurement_id | measurement_value |     measurement_time      |
+|-----------------|-------------------|---------------------------|
+|      131233     |      1109.51      | 2022-07-10 09:00:00      |
+|      135211     |      1662.74      | 2022-07-10 11:00:00      |
+|      523542     |      1246.24      | 2022-07-10 13:15:00      |
+|      143562     |      1124.50      | 2022-07-11 15:00:00      |
+|      346462     |      1234.14      | 2022-07-11 16:45:00      |
+
+
+</details>
+
+<details>
+<summary>
+Output
+</summary>
+</br>
+
+| measurement_day         | odd_sum  | even_sum |
+|-------------------------|----------|----------|
+| 2022-07-10 00:00:00 | 2355.75  | 1662.74  |
+| 2022-07-11 00:00:00 | 1124.50  |   1234.14   |
+
+
+</details>
+
+---

Odd and Even Measurements/schema.sql

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+CREATE TABLE measurements (
+    measurement_id INTEGER,
+    measurement_value DECIMAL,
+    measurement_time TIMESTAMP
+);
+
+INSERT INTO measurements (measurement_id, measurement_value, measurement_time)
+VALUES
+    (131233, 1109.51, '2022-07-10 09:00:00'),
+    (135211, 1662.74, '2022-07-10 11:00:00'),
+    (523542, 1246.24, '2022-07-10 13:15:00'),
+    (143562, 1124.50, '2022-07-11 15:00:00'),
+    (346462, 1234.14, '2022-07-11 16:45:00');
+    
+COMMIT;

Odd and Even Measurements/solution.sql

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+WITH cte AS (
+    SELECT
+        measurement_id,
+        measurement_value,
+        measurement_time,
+        ROW_NUMBER() OVER(
+            PARTITION BY TO_CHAR(measurement_time, 'YYYY-MM-DD')
+            ORDER BY
+                measurement_time
+        ) rn
+    FROM
+        measurements
+)
+SELECT
+    DATE_TRUNC('day', measurement_time) measurement_day,
+    SUM(measurement_value) FILTER(
+        WHERE
+            MOD(rn, 2) = 1
+    ) odd_sum,
+    SUM(measurement_value) FILTER(
+        WHERE
+            MOD(rn, 2) = 0
+    ) even_sum
+FROM
+    cte
+GROUP BY
+    DATE_TRUNC('day', measurement_time)
+ORDER BY
+    DATE_TRUNC('day', measurement_time);

iqsql.md

@@ -2,4 +2,5 @@
 2. Employees Hiring [Difficult]
 3. Highest-Grossing Items
 4. Manager with at least 5 direct reportees
-5. Qualifying Criteria
+5. Odd and Even Measurements
+6. Qualifying Criteria