1. Data Base Concepts

2. Origin of DB Concept Data base concept of military system origin –Probable source is SDC circa 1960 – a RAND corporation spin-off doing USAF systems –SDC made deliberate attempts to promote “systems approach” for corporate management Crucial Characteristics –Constantly updated –Accessed interactively (“real-time”) –Shared between users/systems, gives different views to each

3. DB in Corporate World “Data base” concept crosses over to corporate use in early 1960s “Total Systems Concept” – (aka Management Information System) –Integrated command system for management – real time, on-line –Data base gains scattered usage as crucial, shared “bucket of facts” for this system Discussion of DB predates discussion of DBMS by about seven years.

4. File Management Software As old as corporate computing –First documented in GE, mid-1950s –Generalized set of subroutines to update, query, maintain sequential files Applications keep separate files –But coding, altering, sharing become easier By mid-1960s, becoming more sophisticated –Offered as commercial products –Working with new random-access devices Often called “Information Management” software (GIS, IMS etc)

5. A File Based System, 1962

6. State of Play circa 1967 Data base concept is –Fashionable –Widely promoted as key to MIS –Vaporware, revolutionary –Real-time, on-line, “total system” –Closely tied to information retrieval File management software is –Growth area –Slowly evolving –Practical, batch-oriented, evolutionary

7. The Information Pyramid “Information” turns control of low-level administration into a claim to strategic centrality in a new vision of management Bottom level of the pyramid is the “data base”

8. Data Base Management System New concept “Data Base Management System” –At last! File Management System meets Data Base. Appears circa 1968 –CODASYL Data Base Task Group –Originally in context of extensions to COBOL –Based on consideration of current file management products, directions for future.

9. ANSI-SPARC Three-level Architecture

10. DBMS – Foundational Concept DBMS as software layer between data, users –Different interfaces, languages for Programs & programmers Ad-hoc managerial reporting Data definition maintenance and administration Sets up links between files –BUT rigid, standardized format remain

11. Components of a DBMS

12. Implications DBMS concept –Shapes evolution of modern computing –Underlies interest in “information/data as strategic resource” from mid-70s onward –Aids in corporate information system development, maintenance But at a price –New concept of database is narrower –More general information retrieval problems are excluded

13. DBMS For Corporate Applications Advantages: –easier reporting, program independence from details of data, –faster application development, –easier maintenance –Aids integration of different applications Disjoint with organizational hopes for data base as savior of MIS concept! –Still unable to deliver on initial dream –More for programmers than managers

14. Not One Big Database Big central database doesn’t work Finish up with dozens/hundreds of little data bases –Physically separate –All incomplete –Different data formats –Different concepts of data Dominant model is “relational” (eg Oracle) –Good for updating –Flexible –Can be slow & complex to extract data for reports

15. From Recent DB Textbook Top (strategic) Middle (tactical) Lower (operational) Individual operational databases Summarized, integrated operational databases External data sources and summarized, tactical databases Operational databases Management Hierarchy

16. Data Warehouse Concept Emerges early 1990s One big DB for everything has failed, so –Leave “transactional” systems spread out (physically, organizationally), BUT –Make a second, read-only copy of everything in a centralized “data warehouse”. Update regularly. Lots of work for consultants –Copying, “cleaning”, reformatting data –Restructuring data around business areas and for easy querying –Providing query tools for managerial users

17. Data Warehouse Information Flows