Databases

• A collection of data that conforms with a Data Model
• Often implemented via a DBMS
• Queried using Relational Query Languages

Relational Database

• A set of relations
• Relation: made up of two parts
  • Schema: specifies name of relations, plus name and type of each column
  • Instance: a table, with rows and columns (cardinality (number of rows) vs degree/arity (number of columns))
• Can think of a relation as a set of rows or tuples (i.e. all rows are distinct)