7.3 Designing Databases - keeping track of entities, attributes, and relationships. Records are subdivided into segments. Parent segments can have many children. Children must have one parent each. Data are physically linked via pointers.
Parents can have multiple children.
Children can have multiple parents. Tables sometimes called files. Data can be related as long as both tables share a common data element. Project - Creates a subset consisting of columns in a table. Join - Combines relational table to provide more information.