ABSTRACT
This chapter shows how the relational database model is used from an application perspective. A relational database model contains tables, where rows in tables are accessed using a computer programming language called Structured Query Language (SQL). A declarative programming language describes what we are coding without describing how the problem is solved, which can be difficult to understand, because declarative code requires all instructions in a single complex instruction. IBM created the original relational database technology, and SQL was created as an uncomplicated, non-procedural way of accessing data from an IBM-created relational database. A relational database should automatically create an index for a primary key or for a unique key column.
