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Working with self-referential database relationships
Working with self-referential database relationships
Order ID 53563633773 Type Essay Writer Level Masters Style APA Sources/References 4 Perfect Number of Pages to Order 5-10 Pages Description/Paper Instructions
Working with self-referential database relationships
Self-referential database relationships, also known as recursive relationships, occur when a table contains a foreign key that references the same table. In other words, a record in a table refers to another record in the same table. This type of relationship can be used to model hierarchical structures, such as organizational charts, family trees, or product categories.
To illustrate this concept, let’s consider a simple example of a table called “employees” that contains information about employees in a company. Each employee has a unique ID, a name, a job title, and a manager ID that references another employee in the same table who is their manager. The manager ID is a foreign key that creates a self-referential relationship between the employees table and itself.
Here is an example of how the employees table might look like:
ID Name Job Title Manager ID
1 John Smith CEO NULL
2 Jane Doe COO 1
3 Bob Brown CTO 1
4 Alice Lee Developer 3
5 Tom Davis Developer 3
6 Mary White Designer 2
7 Ann Black Designer 2
In this example, John Smith is the CEO of the company and has no manager, so his manager ID is NULL. Jane Doe and Bob Brown report to John Smith, so their manager ID is 1. Bob Brown is the CTO and has two developers, Alice Lee and Tom Davis, reporting to him, so their manager ID is 3. Finally, Jane Doe has two designers, Mary White and Ann Black, reporting to her, so their manager ID is 2.
To query this data, we can use a recursive query that traverses the hierarchy of employees by joining the employees table to itself on the manager ID foreign key. Here is an example of a recursive query that returns the name and job title of all employees and their respective managers:
vbnet
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WITH RECURSIVE employee_hierarchy AS (
SELECT id, name, job_title, manager_id, 0 AS level
FROM employees
WHERE manager_id IS NULL
UNION ALL
SELECT e.id, e.name, e.job_title, e.manager_id, eh.level + 1
FROM employees e
JOIN employee_hierarchy eh ON eh.id = e.manager_id
)
SELECT name, job_title, level, REPEAT(‘ ‘, level) || name AS indented_name
FROM employee_hierarchy
ORDER BY level, id;
This query uses a common table expression (CTE) with the RECURSIVE keyword to define a recursive subquery called “employee_hierarchy”. The initial query selects all employees who have no manager (i.e., the CEO) and assigns a level of 0 to them. The recursive part of the query selects all employees who have a manager and joins them to their respective managers in the employee_hierarchy subquery, increasing their level by 1. The result is a hierarchical tree of employees that can be ordered by level and ID.
The output of this query would be:
Name Job Title Level Indented Name
John Smith CEO 0 John Smith
Jane Doe COO 1 Jane Doe
Bob Brown CTO 2 Bob Brown
Alice Lee Developer 3
Working with self-referential database relationships
RUBRIC
QUALITY OF RESPONSE NO RESPONSE POOR / UNSATISFACTORY SATISFACTORY GOOD EXCELLENT Content (worth a maximum of 50% of the total points) Zero points: Student failed to submit the final paper. 20 points out of 50: The essay illustrates poor understanding of the relevant material by failing to address or incorrectly addressing the relevant content; failing to identify or inaccurately explaining/defining key concepts/ideas; ignoring or incorrectly explaining key points/claims and the reasoning behind them; and/or incorrectly or inappropriately using terminology; and elements of the response are lacking. 30 points out of 50: The essay illustrates a rudimentary understanding of the relevant material by mentioning but not full explaining the relevant content; identifying some of the key concepts/ideas though failing to fully or accurately explain many of them; using terminology, though sometimes inaccurately or inappropriately; and/or incorporating some key claims/points but failing to explain the reasoning behind them or doing so inaccurately. Elements of the required response may also be lacking. 40 points out of 50: The essay illustrates solid understanding of the relevant material by correctly addressing most of the relevant content; identifying and explaining most of the key concepts/ideas; using correct terminology; explaining the reasoning behind most of the key points/claims; and/or where necessary or useful, substantiating some points with accurate examples. The answer is complete. 50 points: The essay illustrates exemplary understanding of the relevant material by thoroughly and correctly addressing the relevant content; identifying and explaining all of the key concepts/ideas; using correct terminology explaining the reasoning behind key points/claims and substantiating, as necessary/useful, points with several accurate and illuminating examples. No aspects of the required answer are missing. Use of Sources (worth a maximum of 20% of the total points). Zero points: Student failed to include citations and/or references. Or the student failed to submit a final paper. 5 out 20 points: Sources are seldom cited to support statements and/or format of citations are not recognizable as APA 6th Edition format. There are major errors in the formation of the references and citations. And/or there is a major reliance on highly questionable. The Student fails to provide an adequate synthesis of research collected for the paper. 10 out 20 points: References to scholarly sources are occasionally given; many statements seem unsubstantiated. Frequent errors in APA 6th Edition format, leaving the reader confused about the source of the information. There are significant errors of the formation in the references and citations. And/or there is a significant use of highly questionable sources. 15 out 20 points: Credible Scholarly sources are used effectively support claims and are, for the most part, clear and fairly represented. APA 6th Edition is used with only a few minor errors. There are minor errors in reference and/or citations. And/or there is some use of questionable sources. 20 points: Credible scholarly sources are used to give compelling evidence to support claims and are clearly and fairly represented. APA 6th Edition format is used accurately and consistently. The student uses above the maximum required references in the development of the assignment. 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The paper has slight errors within the paper. This can include small errors or omissions with the cover page, abstract, page number, and headers. There could be also slight formatting issues with the document spacing or the font Additionally the paper might slightly exceed or undershoot the specific number of required written pages for the assignment. 10 points: Student provides a high-caliber, formatted paper. This includes an APA 6th edition cover page, abstract, page number, headers and is double spaced in 12’ Times Roman Font. Additionally, the paper conforms to the specific number of required written pages and neither goes over or under the specified length of the paper.
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