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ER Model Justification

Suggest a database design for an internet forum, where users from across the world can read, write, and comment on texts on various topics. Your design needs to support the following. • The system ...
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ER diagram Verification

An airplane company needs a database. Its desired design is described below. For every airplane owned by the company the system needs to store its registration number, which is unique for every ...
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Do I need to populate member id with eg address email?

I am creating a logical model based on the picture I attached. Based on this, do I need to give attributes for example to members? Or can I still create a logical model with just the information ...
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In an ER diagram, can an entity know information about a non-directly connected entity?

Imagine a simple database like this: [credit card] --- has --- [customer] --- places --- [order] Of course the order would know which customer placed it, but would it know which credit card the ...
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Using array VS separate table JOIN for many to many relationship

I have a use case where I need to create entity in postgresql to store some configurations. Example of two rows for configuration is below: ConfigurationCode OperationOne OperationOneValue ...
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61 views

Confusion regarding Weak and Strong Entity types!

Apologies if this is a trivial question, I recently started studying about E.R. Model. Let me try to clarify my doubt using an example. Consider the two entities,Customer and Loan in a relationship ...
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75 views

Mariadb Triggers after multiple insert, update one table one one time

CREATE TRIGGER after_composers_insert AFTER INSERT ON composers FOR EACH ROW UPDATE listings SET composer_name = NEW.composer_name WHERE composer_id = NEW.composer_id; CREATE TRIGGER ...
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52 views

How can I transform an exclusive constraint relationship from ER to RM model?

Let say we have two entities TEACHER and COURSE. There are two relationships between them. A TEACHER can teaches a COURSE, and also can learn a COURSE, however, the TEACHER cannot teach and learn a ...
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93 views

Is it good to join on different tables depending on discrimination column?

I want to build a MySQL database with different trading card, all belonging to different games. Each card, depending on the game, has several properties. For example : A Magic: The Gathering card has ...