Principles of Database Design, Part I AIMS 2710 R. Nakatsu

File-Processing Systems

Problems with File-Processing Systems n Data are separated and isolated n Data are often duplicated n Incompatible data files

DBMS Relationships

The Relational Model n Data is represented in two-dimensional tables  Each of the tables is a matrix consisting of a series of row/column intersections  Files are called tables or relations  Fields (i.e. columns) of the tables are called attributes  Records (i.e. rows) of the tables are called tuples (rarely used terminology) n Information in more than one table can be easily extracted and combined

TableRowColumn FileRecordField RelationTupleAttribute Related Terminology: Three ways to refer to the same thing

What is a database? n A database is an integrated collection of logically related data elements. A database consolidates records previously stored in separate files. n A database can be viewed as the topmost element of a data hierarchy:  database (a set of related files)  file (a collection of related records)  record (a group of logically related fields)  field (an attribute)  character (single alphabet, number, or other symbol)

Database Management System (DBMS) A DBMS (database management system) is a set of computer programs that is used to create, maintain, and provide controlled access to user databases What are some of the DBMS products on the marketplace today?

DBMS: Main Functions n Data definition  Define what data is stored, the type of data, how the data is related.  Specify how the data can be formatted and validated n Data manipulation  You can select which data you want, filter it, sort it, join it with other data, summarize it (querying data) n Application Development  Graphical tools to develop menus, forms, and reports n Data control  Allows you to specify security, as well as how the data can be shared.  Backup and recovery tools