One Pager Cheat Sheet

• Databases are essential for modern living, making data accessible and efficient to use with the traditional relational database model and its use of `structured query language (SQL).**
• The relational database model relies on Entities, their Attributes, Value Sets, Key Attributes and the different types of Relations between them.
• Entities are real world objects described as sets of attributes, that have associated values and key attributes used for identification and facilitate data representation, organization and retrieval.
• The Relational Data Model uses tables to represent data, consists of relation schemas and constraints, and allows entities to be joined by outer keys.
• The key constraints, entity integrity constraints, and referential constraints help to maintain the accuracy and integrity of the data in the relational schema.
• Relational algebra is a theory that uses algebraic structures with well-founded semantics to model data, define queries and apply operations such as projection, selection, product, renaming, union, intersection and difference to manipulate relations.
• The union of two relations R and S will include elements from both R and S, making this statement false.
• Joining creates a new relation containing elements of both R and S.