Re: understand basics - multiple cars in a database - selection of one

David Johnston wrote
> cars-properties

Note that typically "properties" of an object/entity are modeled as
attributes/columns on the entity table.

cars [ carid serial, car_make text, car_model text, car_year text]

as opposed to separate tables.  That main reason for this is that each
property has a specific data type to which correct values must conform.  A
generic "cars-properties" table would require that all property values be
stored as text.

Note that it is also valid to define cars like:

cars [ carid serial, car_properties hstore|json ]

so that the properties are a simple key-value table.  A combination of both
can work as well.

This is where "Database Design" comes into play and as mentioned many
excellent books exist on the topic.  Once you have a design you then develop
whatever UI elements that are needed to properly interact with it.  While UI
is most important there is ample room for layering and facade-ing that
settling for a known sub-optimal database design will likely be painful in
the long-run.

David J.




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