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True or false: an object instance occupies 1 row in its corresponding RDBMS table

 
Benjamin Weaver
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Assume a Car object. A Car has 4 doors and one engine. A Car can carry one or more Persons, and one or more LaptopComputers.

The code might be:




Let's assume we want to search on all Cars having a laptopComputer of a certain COMPUTER_TYPE, or Person with a certain lastName.

Wouldn't the RDBMS mapping for class Car consist of 3 tables? I would assume 3 tables. Yes, even an RDBMS table for the Vector laptopComputers, which contains nothing more than simple Strings. Thus:

CAR_TABLE, PERSON_TABLE, LAPTOPCOMPUTER_TABLE.

with CAR_TABLE standing in one-to-many relation with both PERSON_TABLE and LAPTOPCOMPUTER_TABLE

I would assume that for every Vector (or any other List, Collection, Array, etc.) you would map a separate table in the RDBMS.


I.e. I assume that an instance of a Car object would never occupy more than 1 row in the RDBMS CAR_TABLE.

is this right?
 
Paul Sturrock
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Eclipse IDE Hibernate Java
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That would be a sensible assumption. How this would be implemented would depend on which Object-Relational Mapping technology you used, and how you decided to map it, but typically something that is a definable type (such as your Car class) would correspond to one row in one table.
 
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