Lecture 7. Transformations from ER diagrams to SQL Tables

* Entity – directly to a SQL table

* Many-to-many binary relationship – directly to a SQL table, taking the 2 primarykeys in the 2 entities associated with this relationship as foreign keys in the new table

* One-to-many binary relationship – primary key on “one” side entity copied as aforeign key in the “many” side entity’s table

* Recursive binary relationship – same rules as other binary relationships

* Ternary relationship – directly to a SQL table, taking the 3 primary keys of the 3entities associated with this relationship as foreign keys in the new table

* Attribute of an entity – directly to be an attribute of the table transformed from thisentity

* Generalization super-class (super-type) entity – directly to a SQL table

* Generalization subclass (subtype) entity – directly to a SQL table, but with theprimary key of its super-class (super-type) propagated down as a foreign key into its table

* Mandatory constraint (1 lower bound) on the “one” side of a one-to-many relationship – the foreign key in the “many” side table associated with the primary key inthe “one” side table should be set as “not null” (when the lower bound is 0, nulls are allowed as the default in SQL)

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