Lecture 0

• Tables = relation
• Columns = attributes
• Schema = title of columns
• Records = tuples
• Instance = snapshot: everything except attributes
• Domain of an attribute: type of values that attributes can take (float, int…)
• To uniquely refer to a tuple or row in a schema, we need keys.
• Superkey: a set of one or more attributes that taken together uniquely identify a tuple in the relation.
• Candidate keys: minimal superkeys - a superkey requiring the least entries to define a tuple.
• Primary keys are candidate keys chosen by the database designer to distinguish between tuples.