BMGT 402 Lecture Notes - Lecture 3: Superkey, Candidate Key, Relational Model

• School: University of Maryland
• Department: Business and Management
• Course: BMGT 402
• Professor: Woei- Jyh Lee

Document Summary

Domain : set of allowable values for 1+ attributes. Degree : # of attributes in a relation. Cardinality : # of tuples in a relation. Domain definition for street names: character: size 25 max. Relation schema: named relation defined by set of attribute and domain name pairs. Relational database schema: set of relation schemas each with a distinct name. Relation name is distinct from all other relation names in schema. Each cell of relation has 1 atomic value. Attribute values are all from the same domain (the column contains data with same type of value: number vs character, etc. ) Each attribute has a distinct name (columns have different names) The order of tuples/attributes is not significant (the order of rows/columns) Alt + enter to enter multiple rows in one field box in excel. Uniquely identifies a tuple in the relation (ex: uid at university of maryland) One attribute or combo of attributes in a data table/relation.