Before the Advent of Database Systems
Read chapter 1, which begins by discussing fundamental data concepts. The study of databases is an extension of the study of data in programming. The study of databases as a discipline was motivated by a variety of factors: the increasing size and complexity of software systems, the need to share data, and the need to be able to maintain and secure data effectively.
Data is a collection of symbols used to represent numbers, text, pictures, videos, audio, and so on. How this data is represented gives the meaning (or semantics) for the symbols. Additional semantics are provided by the relationships that data has with other data. In programming, the semantics of data is provided by program documentation, as well as the programming language used to create the program. In databases, the semantics of the data is provided by a data model, which includes the representation of the data, relationships among the data, and metadata (which is data that defines other data).
Semantics makes data useful, and we define useful data as information. Sometimes, the terms 'data' and 'information' appear as synonyms. However, they are different: all information is data, but not all data is information. The type and amount of semantics determines the usefulness of some given data. Usefulness is also relative to a given user. Data may not be useful to some users, but very useful to others.
Identifying data and information and organizing them into a data model typically occurs in software requirements analysis and design. Current work in the field of databases addresses techniques that support building and storing data models, and using them to discover meaning (or information) in large volumes of data.