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129 lines
5.3 KiB
HTML
129 lines
5.3 KiB
HTML
<p>Table: <code>drivers</code></p>
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<pre>
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+-------------+---------+
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| Column Name | Type |
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+-------------+---------+
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| driver_id | int |
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| driver_name | varchar |
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+-------------+---------+
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driver_id is the unique identifier for this table.
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Each row contains information about a driver.
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</pre>
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<p>Table: <code>trips</code></p>
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<pre>
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+---------------+---------+
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| Column Name | Type |
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+---------------+---------+
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| trip_id | int |
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| driver_id | int |
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| trip_date | date |
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| distance_km | decimal |
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| fuel_consumed | decimal |
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+---------------+---------+
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trip_id is the unique identifier for this table.
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Each row represents a trip made by a driver, including the distance traveled and fuel consumed for that trip.
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</pre>
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<p>Write a solution to find drivers whose <strong>fuel efficiency has improved</strong> by <strong>comparing</strong> their average fuel efficiency in the<strong> first half</strong> of the year with the <strong>second half</strong> of the year.</p>
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<ul>
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<li>Calculate <strong>fuel efficiency</strong> as <code>distance_km / fuel_consumed</code> for <strong>each</strong> trip</li>
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<li><strong>First half</strong>: January to June, <strong>Second half</strong>: July to December</li>
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<li>Only include drivers who have trips in <strong>both halves</strong> of the year</li>
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<li>Calculate the <strong>efficiency improvement</strong> as (<code>second_half_avg - first_half_avg</code>)</li>
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<li><strong>Round </strong>all<strong> </strong>results<strong> </strong>to<strong> <code>2</code> </strong>decimal<strong> </strong>places</li>
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</ul>
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<p>Return <em>the result table ordered by efficiency improvement in <strong>descending</strong> order, then by driver name in <strong>ascending</strong> order</em>.</p>
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<p>The result format is in the following example.</p>
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<p> </p>
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<p><strong class="example">Example:</strong></p>
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<div class="example-block">
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<p><strong>Input:</strong></p>
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<p>drivers table:</p>
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<pre class="example-io">
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+-----------+---------------+
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| driver_id | driver_name |
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+-----------+---------------+
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| 1 | Alice Johnson |
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| 2 | Bob Smith |
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| 3 | Carol Davis |
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| 4 | David Wilson |
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| 5 | Emma Brown |
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+-----------+---------------+
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</pre>
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<p>trips table:</p>
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<pre class="example-io">
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+---------+-----------+------------+-------------+---------------+
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| trip_id | driver_id | trip_date | distance_km | fuel_consumed |
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+---------+-----------+------------+-------------+---------------+
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| 1 | 1 | 2023-02-15 | 120.5 | 10.2 |
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| 2 | 1 | 2023-03-20 | 200.0 | 16.5 |
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| 3 | 1 | 2023-08-10 | 150.0 | 11.0 |
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| 4 | 1 | 2023-09-25 | 180.0 | 12.5 |
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| 5 | 2 | 2023-01-10 | 100.0 | 9.0 |
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| 6 | 2 | 2023-04-15 | 250.0 | 22.0 |
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| 7 | 2 | 2023-10-05 | 200.0 | 15.0 |
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| 8 | 3 | 2023-03-12 | 80.0 | 8.5 |
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| 9 | 3 | 2023-05-18 | 90.0 | 9.2 |
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| 10 | 4 | 2023-07-22 | 160.0 | 12.8 |
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| 11 | 4 | 2023-11-30 | 140.0 | 11.0 |
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| 12 | 5 | 2023-02-28 | 110.0 | 11.5 |
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+---------+-----------+------------+-------------+---------------+
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</pre>
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<p><strong>Output:</strong></p>
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<pre class="example-io">
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+-----------+---------------+------------------+-------------------+------------------------+
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| driver_id | driver_name | first_half_avg | second_half_avg | efficiency_improvement |
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+-----------+---------------+------------------+-------------------+------------------------+
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| 2 | Bob Smith | 11.24 | 13.33 | 2.10 |
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| 1 | Alice Johnson | 11.97 | 14.02 | 2.05 |
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+-----------+---------------+------------------+-------------------+------------------------+
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</pre>
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<p><strong>Explanation:</strong></p>
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<ul>
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<li><strong>Alice Johnson (driver_id = 1):</strong>
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<ul>
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<li>First half trips (Jan-Jun): Feb 15 (120.5/10.2 = 11.81), Mar 20 (200.0/16.5 = 12.12)</li>
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<li>First half average efficiency: (11.81 + 12.12) / 2 = 11.97</li>
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<li>Second half trips (Jul-Dec): Aug 10 (150.0/11.0 = 13.64), Sep 25 (180.0/12.5 = 14.40)</li>
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<li>Second half average efficiency: (13.64 + 14.40) / 2 = 14.02</li>
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<li>Efficiency improvement: 14.02 - 11.97 = 2.05</li>
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</ul>
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</li>
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<li><strong>Bob Smith (driver_id = 2):</strong>
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<ul>
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<li>First half trips: Jan 10 (100.0/9.0 = 11.11), Apr 15 (250.0/22.0 = 11.36)</li>
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<li>First half average efficiency: (11.11 + 11.36) / 2 = 11.24</li>
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<li>Second half trips: Oct 5 (200.0/15.0 = 13.33)</li>
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<li>Second half average efficiency: 13.33</li>
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<li>Efficiency improvement: 13.33 - 11.24 = 2.10 (rounded to 2 decimal places)</li>
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</ul>
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</li>
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<li><strong>Drivers not included:</strong>
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<ul>
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<li>Carol Davis (driver_id = 3): Only has trips in first half (Mar, May)</li>
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<li>David Wilson (driver_id = 4): Only has trips in second half (Jul, Nov)</li>
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<li>Emma Brown (driver_id = 5): Only has trips in first half (Feb)</li>
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</ul>
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</li>
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</ul>
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<p>The output table is ordered by efficiency improvement in descending order then by name in ascending order.</p>
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</div>
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