Data Modeling - Why are recursive relationships are bad? How do you resolve them?

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Why are recursive relationships are bad? How do you resolve them?

Total Answers and Comments: 3

Last Update: November 12, 2007

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Submitted by: Jeetendra Nalawade

We have used a different way of maintaning recursive relationship. We have created a ancestry table which will give the childs for each entry upto n th level. This way you can fire queries directly to get the child upto any specific level.

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June 24, 2005 20:25:03

John

RE: Why are recursive relationships are bad? How do you resolve them?

Recursive relationships are an interesting and more complex concept than the relationships you have seen in the previous chapters such as a one-to-one one-to-many and many-to-many. A recursive relationship occurs when there is a relationship between an entity and itself. For example a one-to-many recursive relationship occurs when an employee is the manager of other employeess. The employee entity is related to itself and there is a one-to-many relationship between one employee (the manager) and many other employees (the people who report to the manager). Because of the more complex nature of these relationships we will need slightly more complex methods of mapping them to a schema and displaying them in a stylesheet.

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July 21, 2005 00:45:58

ritwik roy

RE: Why are recursive relationships are bad? How do you resolve them?

using the concept of self join may be a solution to this problem. e.g if a table called employees contains three fields like emp_id name and manager_id and we will have to find out the name of the manager for each employee then we can use the following code
select a.name b.name
from employees a employees b
where a.manager_id b.emp_id

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November 12, 2007 04:57:35

Jeetendra Nalawade

RE: Why are recursive relationships are bad? How do yo...

We have used a different way of maintaning recursive relationship. We have created a ancestry table which will give the childs for each entry upto n th level. This way you can fire queries directly to get the child upto any specific level.

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