A primary key is a column (or set of columns) in a relational database table that uniquely identifies each row; NULL values and duplicates are not allowed. A foreign key is a column that references the primary key of another table, defining relationships between tables and enforcing referential integrity. For example, setting a department code as a foreign key in an employee table prevents references to non-existent departments.

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• 2013h25h #55関係データベースを使い“社員”表と“部署”表を作成して社員情報を管理する。 “社員”表と“部署”表に、必要に応じて設定する主キーと外部キーの適切な組合せはどれか…