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Well someone could help me with my MER I’m wondering if I’m using the correct logic in relationships and cardinalities:
a report may have one or more services
1 - n
a request has one or more reports
report has only one request
a report may have one or more services ( ex in the report with ID 1 two services were used) and service can be part of several reports
A request generates a newsletter ( 1:1 )
these two relationships are confusing me
What is the justification in your requirements for you to have boletim_request as an entity apart since the relationship is 1:1?
– anonimo
@anonymous in case every request generates a newsletter this newsletter will contain the report of services and parts
– Joao Spirit
But only with the attributes listed in your model continues to make sense?
– anonimo
I have not yet finished this relationship he will receive more attributes and fk, my doubt is more in relation to my request relationship and services .
– Joao Spirit
A request can have 0 or more services and a service can be part of n requests.
– Joao Spirit
An N:N relationship is modeled after the way you did: an auxiliary entity representing the relationship and two 1:N (or 0:N) relationships of this auxiliary entity with each of the original entities.
– anonimo
@anonymo did not understand very well, could you for an answer how I can improve this? Type I have taken into account a Sales relationship / Products n:n one or more products are part of the sale and a sale has one or more products and then has if an item_sale table .
– Joao Spirit
I tried to apply it in this situation because it’s an n:n relationship
– Joao Spirit