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Asked: 2024-09-24T21:44:56+05:30 In:

Craft a complex SQL query scenario based on the following criteria: Given a database containing employee records, write a query to identify employees who have worked on multiple projects but have not received any bonuses. Include the conditions for filtering the employees and explain the reasoning behind your query structure.

I’m diving into a bit of SQL and could use your help with a tricky query I’m trying to craft. So, here’s the scenario: imagine we have a database that contains records of employees, their projects, and any bonuses they’ve received. I need to find out which employees have worked on multiple projects but totally missed out on any bonuses.

To clarify, the database has three main tables:

1. **employees**: This table has details about employees including `employee_id`, `name`, and `department`.

2. **projects**: This table lists the projects with `project_id` and project details.

3. **employee_projects**: This one acts as a junction table linking `employee_id` to `project_id`, showing which employees have worked on which projects.

4. **bonuses**: A table recording bonus distributions with fields like `employee_id` and `bonus_amount`.

Now, the thing I need to figure out is how to pull info from all these tables to get a list of employees who meet the criteria: they’ve worked on more than one project but haven’t received a single bonus.

Here’s how I’m thinking of structuring the query:

1. **Start with the `employee_projects` table** to count the number of projects each employee has worked on. I’d use a `GROUP BY` clause on `employee_id` and then a `HAVING` clause to ensure the count of projects is greater than one.

2. **Next, join this result with the `bonuses` table** to filter out employees who have received bonuses. Here I’d want to ensure that any employees listed do not exist in the bonuses table at all.

3. **Finally, join back to the `employees` table** to get the employee names so the results are meaningful.

I’m curious if anyone has tackled something similar or has a different approach they’d suggest? Maybe there’s a more efficient way to do it, or tips on ensuring we don’t miss any employees who might fit this description. Looking forward to seeing what you all think!

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    2 Answers


    1. To achieve your goal of identifying employees who have worked on multiple projects without receiving any bonuses, you can start with an SQL query that effectively combines the necessary operations. First, you’ll want to use the employee_projects table to group records by employee_id and count the number of projects associated with each employee. Use the HAVING clause to filter for employees who have worked on more than one project. The basic structure of this part of the query would look something like this:

      SELECT employee_id
FROM employee_projects
GROUP BY employee_id
HAVING COUNT(project_id) > 1;

      Next, to ensure that these employees have not received any bonuses, you’ll employ a LEFT JOIN with the bonuses table to filter out those who do have bonus records. Use a WHERE clause to check for NULL values in the bonus table, meaning that the employee has no corresponding entry in the bonuses table. Finally, join this result with the employees table to fetch meaningful employee names. Here’s how the entire query might be structured:

      SELECT e.name
FROM (
    SELECT employee_id
    FROM employee_projects
    GROUP BY employee_id
    HAVING COUNT(project_id) > 1
) ep
LEFT JOIN bonuses b ON ep.employee_id = b.employee_id
JOIN employees e ON ep.employee_id = e.employee_id
WHERE b.employee_id IS NULL;

      This query effectively pulls together all the necessary information to meet your criteria.




    2. SQL Query Help

      Help with SQL Query

      So, I’ve been working on this query and here’s what I have in mind:

              SELECT e.employee_id, e.name
        FROM employees e
        JOIN employee_projects ep ON e.employee_id = ep.employee_id
        GROUP BY e.employee_id, e.name
        HAVING COUNT(ep.project_id) > 1
        AND e.employee_id NOT IN (SELECT employee_id FROM bonuses);

      Here’s the breakdown:

      • I’m using a JOIN to connect the employees table with employee_projects
      • Then I’m grouping by the employee id and name, so I can count how many projects each employee has worked on.
      • With the HAVING clause, I filter to get only those who’ve worked on more than one project.
      • Lastly, I check that the employee ID is not in the bonuses table using a subquery, which should give me the employees with no bonuses.

      Does this make sense? Just trying to wrap my head around it, and I hope I’m on the right track! If anyone has other ideas or tips, I’d love to hear them!


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