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Is it mandatory to include every entities mentioned in the description when creating an er diagram. The description don't give any information about relationship between the entity mentioned before and other entities. So if we take minimum requirements to show case the scenario, is it necessary to include that entity also?

Assume this question:

In a Cafe Shop, several types of food items are there. A customer places his/her order. A serviceman can serve multiple orders but an order will be serviced by only one serviceman. A customer can place more than one order. Which of the following statement(s) is (are) true?

a) There will be minimum three entities in the E-R dingram.

b) There will be minimum four entities in the E-R diagram.

c) Minimum two relationships will be required in the E-R diagram to modeled the scenario.

d) Minimum three relationships will be required in the E-R diagram to modeled the scenario.

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    I guess that depends on the assignment you have been given.
    – mustaccio
    Feb 27 at 15:43
  • Hi, and welcome to dba.se! An order can contain multiple items? Schema design is an iterative process.
    – Vérace
    Feb 27 at 16:57
  • Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer.
    – Community Bot
    Feb 27 at 16:57

1 Answer 1

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Is it mandatory to include every entities mentioned in the description when creating an er diagram

Generally speaking, you should tailor the diagram to your audience.

Particularly speaking, since the question looks like school assignment, you should include everything in the description. (But if you are unsure, consider asking teacher for a clarification.)

The description don't give any information about relationship between the entity mentioned before and other entities.

Some things may not be spelt out directly, but they might be inferred by knowing how the system you are modelling (e. g. orders in coffee shop) works.

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