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by johnnyhillbilly 3444 days ago
"Relational" means "tabular". (A "relation" in relational theory is a table with a name, fields with names and types, and the data in the table.)

A "relationship" in an ER diagram maps to a "reference" in relational theory. This is part of the type safety/domain system of RDBMSs.

If these concepts are muddled, SQL will never quite make sense :)
1 comments
dragonwriter 3444 days ago
> "Relational" means "tabular".

Relational database can be expressed in tabular form, but tabular data is not necessarily relational.

> (A "relation" in relational theory is a table with a name, fields with names and types, and the data in the table.)

A relation is a system of one or more functions (in the mathematical sense) each of which has a domain that is a candidate key of the relation and a range that is the composite of the non-key attributes.

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johnnyhillbilly 3444 days ago
Interesting definition. Do you have a source for it. It seems ambiguous.

From the Wikipedia article on relational databases, subsection relational model. "This model organizes data into one or more tables (or "relations") of columns and rows, with a unique key identifying each row. Rows are also called records or tuples."

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