ER Diagram/Data Modelling question
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24-01-2021 - |
Question
I wanted to know how to represent a relationship between two entities which means "atleast".
Eg- A song must be part of atleast one album.
If "A song can be part of one or more than one album" means a one to many relationship between song and album, then what would the ER diagram for the Eg given above be?
Solution
It's represented on an ERD by a double line (called a participation constraint).
If one song can be on many albums, you need a junction table, Like so:
album -+------< album_song >------+- song
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