Confused

Question

In ER-DIAGRAM to Relation conversion :

I can’t understand how to handle the following points

How to deal with one-to-one relationship with any of the entity having total participation in relation?

How to deal with One-to-many relationship with an entity having total participation or both having total participation in the relationship?

How to deal with many-to-many relationship with total participation of one or both the entities in relation?

Comments

Handle as in? Couldn't get your query .

Are you asking how to handle total participation or about the tables to handle the relationships?

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How to convert Er-diagrams to Relations when the following conditions are there! @prashant jha 1

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In case of one-one only 2 relations are required , and the relationship attribute can be kept in either of two.

Same in case one-many , but identifying relationship should be on the many side.

In case of many-many always one extra table has to be created because keeping in either will cause repetition of data.

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Total participation is just another constraint , can be maintained using a NOT NULL clause

Answer 1

1.Only Partial participations-

• One-One:2 Tables, Merge Relation to any of the side.
• Many-One or One-Many:2 Tables, Merge Relation to Many side.
• Many-Many:3 tables (separate table for relation)

2. Any one of the  side has full participation-

• Full participation on Many Side: 2 Tables
• Full Participation on one side: 1 Table

3.Both Side full participation-

• Always one table irrespective of Cardinality.