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138 lines
5.0 KiB
HTML
138 lines
5.0 KiB
HTML
<p>Table: <code>employees</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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| employee_id | int |
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| name | varchar |
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+-------------+---------+
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employee_id is the unique identifier for this table.
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Each row contains information about an employee.
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</pre>
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<p>Table: <code>performance_reviews</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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| review_id | int |
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| employee_id | int |
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| review_date | date |
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| rating | int |
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+-------------+------+
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review_id is the unique identifier for this table.
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Each row represents a performance review for an employee. The rating is on a scale of 1-5 where 5 is excellent and 1 is poor.
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</pre>
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<p>Write a solution to find employees who have consistently improved their performance over <strong>their last three reviews</strong>.</p>
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<ul>
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<li>An employee must have <strong>at least </strong><code>3</code><strong> review</strong> to be considered</li>
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<li>The employee's <strong>last </strong><code>3</code><strong> reviews</strong> must show <strong>strictly increasing ratings</strong> (each review better than the previous)</li>
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<li>Use the most recent <code>3</code> reviews based on <code>review_date</code> for each employee</li>
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<li>Calculate the <strong>improvement score</strong> as the difference between the latest rating and the earliest rating among the last <code>3</code> reviews</li>
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</ul>
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<p>Return <em>the result table ordered by <strong>improvement score</strong> in <strong>descending</strong> order, then by <strong>name</strong> 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>employees table:</p>
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<pre class="example-io">
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+-------------+----------------+
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| employee_id | 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>performance_reviews table:</p>
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<pre class="example-io">
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+-----------+-------------+-------------+--------+
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| review_id | employee_id | review_date | rating |
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+-----------+-------------+-------------+--------+
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| 1 | 1 | 2023-01-15 | 2 |
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| 2 | 1 | 2023-04-15 | 3 |
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| 3 | 1 | 2023-07-15 | 4 |
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| 4 | 1 | 2023-10-15 | 5 |
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| 5 | 2 | 2023-02-01 | 3 |
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| 6 | 2 | 2023-05-01 | 2 |
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| 7 | 2 | 2023-08-01 | 4 |
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| 8 | 2 | 2023-11-01 | 5 |
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| 9 | 3 | 2023-03-10 | 1 |
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| 10 | 3 | 2023-06-10 | 2 |
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| 11 | 3 | 2023-09-10 | 3 |
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| 12 | 3 | 2023-12-10 | 4 |
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| 13 | 4 | 2023-01-20 | 4 |
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| 14 | 4 | 2023-04-20 | 4 |
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| 15 | 4 | 2023-07-20 | 4 |
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| 16 | 5 | 2023-02-15 | 3 |
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| 17 | 5 | 2023-05-15 | 2 |
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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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| employee_id | name | improvement_score |
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+-------------+----------------+-------------------+
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| 2 | Bob Smith | 3 |
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| 1 | Alice Johnson | 2 |
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| 3 | Carol Davis | 2 |
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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 (employee_id = 1):</strong>
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<ul>
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<li>Has 4 reviews with ratings: 2, 3, 4, 5</li>
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<li>Last 3 reviews (by date): 2023-04-15 (3), 2023-07-15 (4), 2023-10-15 (5)</li>
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<li>Ratings are strictly increasing: 3 → 4 → 5</li>
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<li>Improvement score: 5 - 3 = 2</li>
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</ul>
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</li>
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<li><strong>Carol Davis (employee_id = 3):</strong>
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<ul>
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<li>Has 4 reviews with ratings: 1, 2, 3, 4</li>
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<li>Last 3 reviews (by date): 2023-06-10 (2), 2023-09-10 (3), 2023-12-10 (4)</li>
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<li>Ratings are strictly increasing: 2 → 3 → 4</li>
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<li>Improvement score: 4 - 2 = 2</li>
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</ul>
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</li>
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<li><strong>Bob Smith (employee_id = 2):</strong>
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<ul>
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<li>Has 4 reviews with ratings: 3, 2, 4, 5</li>
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<li>Last 3 reviews (by date): 2023-05-01 (2), 2023-08-01 (4), 2023-11-01 (5)</li>
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<li>Ratings are strictly increasing: 2 → 4 → 5</li>
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<li>Improvement score: 5 - 2 = 3</li>
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</ul>
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</li>
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<li><strong>Employees not included:</strong>
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<ul>
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<li>David Wilson (employee_id = 4): Last 3 reviews are all 4 (no improvement)</li>
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<li>Emma Brown (employee_id = 5): Only has 2 reviews (needs at least 3)</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 improvement_score in descending order, then by name in ascending order.</p>
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</div>
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