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72 lines
2.3 KiB
HTML
72 lines
2.3 KiB
HTML
<p>Table: <code>Project</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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| project_id | int |
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| employee_id | int |
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+-------------+---------+
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(project_id, employee_id) is the primary key of this table.
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employee_id is a foreign key to <code>Employee</code> table.
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Each row of this table indicates that the employee with employee_id is working on the project with project_id.
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</pre>
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<p> </p>
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<p>Table: <code>Employee</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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| experience_years | int |
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+------------------+---------+
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employee_id is the primary key of this table. It's guaranteed that experience_years is not NULL.
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Each row of this table contains information about one employee.
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</pre>
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<p> </p>
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<p>Write an SQL query that reports the <strong>average</strong> experience years of all the employees for each project, <strong>rounded to 2 digits</strong>.</p>
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<p>Return the result table in <strong>any order</strong>.</p>
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<p>The query result format is in the following example.</p>
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<p> </p>
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<p><strong class="example">Example 1:</strong></p>
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<pre>
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<strong>Input:</strong>
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Project table:
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+-------------+-------------+
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| project_id | employee_id |
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+-------------+-------------+
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| 1 | 1 |
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| 1 | 2 |
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| 1 | 3 |
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| 2 | 1 |
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| 2 | 4 |
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+-------------+-------------+
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Employee table:
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+-------------+--------+------------------+
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| employee_id | name | experience_years |
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+-------------+--------+------------------+
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| 1 | Khaled | 3 |
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| 2 | Ali | 2 |
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| 3 | John | 1 |
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| 4 | Doe | 2 |
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+-------------+--------+------------------+
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<strong>Output:</strong>
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+-------------+---------------+
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| project_id | average_years |
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+-------------+---------------+
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| 1 | 2.00 |
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| 2 | 2.50 |
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+-------------+---------------+
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<strong>Explanation:</strong> The average experience years for the first project is (3 + 2 + 1) / 3 = 2.00 and for the second project is (3 + 2) / 2 = 2.50
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</pre>
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