Example image of eyePlorer eyePlorer map for 'Relational database': Database Logical schema Relational model Relational database management system Relation (database) Table (database) Edgar F. Codd IBM Almaden Research Center SQL Attribute Tuple Column (database) Row (database) Domain of a function View (database) Abstraction layer Business rule Check Constraint Boolean Source code Application programming interface Declarative programming Procedural programming B+ tree Bitmap index R-tree Relational algebra Relational calculus Set theory Union (set theory) Intersection (set theory) Complement (set theory) Cartesian product Subset Entropy (information theory) Hierarchical database model Network model Object database Object-relational impedance mismatch XML database IBM Microsoft Oracle Corporation MySQL Open source PostgreSQL SQLite Active record pattern Adabas D Alpha (language)