The Architectural Logic of Database Systems

If we look back to pre-database systems and the data units which were in use, we will establish a hierarchy starting with the concept of 'field' used to build 'records' which were in turn used to build higher data units such as 'files'. The file was considered to be the ultimate data unit of information processing and data binding 'monolith'. Moreover, pre­ database systems were designed with one or more programming languages in mind and this in effect restricted independent develop­ ment and modelling of the applications and associated storage structures. Database systems came along not to turn the above three units into outmoded concepts, but rather to extend them further by establishing a higher logical unit for data description and thereby offer high level data manipulation functions. It also becomes possible for computer professionals and other users to view all information processing needs of an organisation through an integrated, disciplined and methodical approach. So, database systems employ the concepts field, record and file without necessarily making them transparent to the user who is in effect offered a high level language to define data units and relation­ ships, and another language to manipulate these. A major objective of database systems is to allow logical manipulations to be carried out independent of storage manipulations and vice versa.

1 Foundations of Databases.- 1.1 Data and Information.- 1.2 Program and File Communication.- 1.3 Program and Meta-file Communication.- 1.4 Towards a Database System.- 1.5 High Level Database Software.- 1.6 Summary.- 1.7 References.- 2 The Logic of the Database Environment.- 2.1 The Principle of Data Independence.- 2.1.1 Physical Independence.- 2.1.2 Logical Independence.- 2.2 Standard Software and the Database.- 2.3 Three Architectural Levels.- 2.3.1. Logical Schema.- 2.3.2 Logical Subschema.- 2.3.3 Internal Schema.- 2.4 Types of Users.- 2.4.1 Database Administrator (DBA).- 2.4.2 System Software Engineer (SSE).- 2.4.3 Applications Analyst.- 2.4.4 Applications Programmer.- 2.4.5 General User.- 2.5 Summary.- 2.6 References.- 3 Data Structures and Data Models.- 3.1 Introduction.- 3.2 Data Structures and Relationships.- 3.2.1 Data Structures on Keys.- 3.2.2 Tree Structures.- 3.3 Hierarchic Data Models.- 3.4 Network Data Models.- 3.5 Relational Data Models.- 3.5.1 Relational Terminology.- 3.5.2 Basic Characteristics of Relational Models.- 3.6 An Example Schema Model.- 3.7 An Example Subschema Model.- 3.8 Summary.- 3.9 References.- 4 The Architecture of Database Software.- 4.1 Introduction.- 4.1.1 Data Types and Qualifiers.- 4.2. Data Description Language (DDL).- 4.2.1 RDL Commands.- 4.3 Data Manipulation Language (DML).- 4.3.1 RDL Commands.- 4.4 Data Storage Description Language (DSDL).- 4.4.1 RDL Commands.- 4.5 Query Language.- 4.5.1 RDL Commands.- 4.6 Query By Example (QBE).- 4.6.1 Example Forms of QBE.- 4.7 Data Dictionary.- 4.7.1 Aims and Objectives.- 4.7.2 The Data Dictionary and the Database.- 4.8 An Overview of Software Integration.- 4.9 Summary.- 4.10 References.- 5 Communicating with Databases in Natural Language.- 5.1 Programming Languages.- 5.2 The PROLOG Programming Language.- 5.3 Natural Language System Architecture.- 5.3.1 The Language PROLOG and the Database.- 5.3.2 Conclusions and Further Research.- 5.4 Communicating with Databases by Voice.- 5.5 Speech Synthesis.- 5.6 Speech Recognition.- 5.7 An Integrated View of Man-Machine Interfaces.- 5.8 Summary.- 5.9 References.- 6 Database Design Methodology.- 6.1 Introduction.- 6.2 Top-Down and Bottom-Up Design.- 6.3 Major Stages in Database Design.- 6.4 Six Mappings.- 6.5 Decomposition and Normalisation.- 6.6 Relationships between Attributes.- 6.7 Key Attributes.- 6.8 The Five Normal Forms.- 6.8.1 First Normal Form (1NF).- 6.8.2 Second Normal Form (2NF).- 6.8.3 Third Normal Form (3NF).- 6.8.4 Fourth Normal Form (4NF).- 6.8.5 Fifth Normal Form (5NF).- 6.8.6 Conclusions.- 6.9 Summary.- 6.10 References.- 7 Canonical Synthesis for Database Design.- 7.1 Introduction.- 7.2 Element Associations.- 7.2.1 Keys, Attributes, and Data Element Groups.- 7.3 Readying the Views for Canonical Synthesis.- 7.3.1 Inconsistent Associations.- 7.3.2 Illegal Associations.- 7.3.3 Normalisation of the Views.- 7.3.3.1 First Normal Form (1NF).- 7.3.3.2 Second Normal Form (2NF).- 7.3.3.3 Third Normal Form (3NF).- 7.3.4 Deviation from Third Normal Form.- 7.4 The Canonical Synthesis Algorithm.- 7.4.1 Merging of the Views.- 7.4.2 Keys and Attributes.- 7.4.3 Concatenated Keys.- 7.4.3.1 Problems with Concatenated Attributes.- 7.4.4 Dealing with M:M Associations.- 7.4.5 Dealing with 1:1 Associations.- 7.4.6 Removal of Redundancies.- 7.4.6.1 Programming Considerations.- 7.4.7 Isolated and Intersecting Attributes.- 7.5 Further Investigations on Canonical Synthesis.- 7.6 Summary.- 7.7 References.- 8 Relational Architecture.- 8.1 Introduction.- 8.2 Domains and Attributes.- 8.3 Manipulation of Relational Tables.- 8.3.1 Union.- 8.3.2 Intersection.- 8.3.3 Difference.- 8.3.4 Selection.- 8.3.5 Projection.- 8.3.6 Join.- 8.3.7 Division.- 8.4 Subschema Definitions.- 8.5 Representing Trees.- 8.5.1 From Table to Tree.- 8.6 Representing Networks.- 8.7 Summary.- 8.8 References.- 9 A Network Database Language.- 9.1 Introduction.- 9.2 Logical Relationships and Set Types.- 9.3 Structural Relationships.- 9.3.1 Order of Record Occurrences.- 9.3.2 Membership of Record Occurrences.- 9.4 Network Database Language.- 9.4.1 Schema Definition.- 9.4.2 Subschema Definition.- 9.4.3 Data Manipulation.- 9.5 Summary.- 9.6 References.- 10 Dictionary of Database Terminology.- 11 Appendix. Example Reports from Canonical Synthesis.- 12 Acronyms.