In relational database terminology, a table is called a ???relation.??? Note that a relation is a table, not a relationship.
Later we will also create means to represent relationships. A relation consists of rows, each of which represents an
instance of the entity type, and of columns, each of which represents one of the attributes of the entity type.
Each row of a relation is called a tuple. Practitioners use the word row more often than tuple, but a tuple is
a row of a table, an instance of a relation, an instance of an entity type. Each tuple consists of the values of the
attributes for that instance of the entity type.
Another word for attribute is field. So, in discussions of relational databases, you must keep in mind these
synonyms: relation and table, tuple and row, attribute and field.
The first step is to create a relation for each strong entity in the data model. Each of the attributes of
the entity type in the data model will become a column name in the relation. At this time one must choose an
attribute, or set of attributes, called a primary key, which will uniquely identify each row of the relation.
The ideal key is short, numeric, and never-changing. The ideal is not always possible to achieve, but it can be
helpful to keep the ideal in mind when choosing a key.
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