An Overview of Database Management Systems

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Overview of Database Management Systems

• Goals:
– DBMS basic concepts – Introduce underlying managerial issues – Prepare for discussion of uses of DBMS, such as OLAP and database mining


Steven O. Kimbrough


Overview of Database Management • What is a database system? – Acomputerized record-keeping system

• Record?
– Think of it as a row in a table, consisting of fields of data – Note: Role of metaphors

• System?
– A general software module that provides all sorts of services: – Create new files and add them to the database – Insert new data into an existing file – Retrieve data from existing files – Update (change) data in existing files – Delete data in existing files – Delete (remove) existing files from the database – And much else: system management features, security, integrity, etc.


Steven O. Kimbrough


Overview of Database Management • Important and fundamental distinctions – System software vs application software – Logical vs physical » See MIS Notes, chapter 1

• System software, e.g.,
– – – – Operating system Language compilers Communications DBMS

• Idea: everybody needs it, so write it once and standardly for all – Reading/writing files (OS) – Storing/retrieving records (DBMS)


Steven O. Kimbrough


Overview of Database Management • Where do database systems come from? – Commercial software vendors » Oracle, DB2, RDB, Ingres, Focus, etc. for mainframes » For Unix, Oracle, Ingres, Informix, etc. » Macs: Mainly Oracle » PCs: Access, Paradox, Oracle, etc.

• Is there more than one kind? Why?
– Yes: flat file systems, network systems, hierarchical systems, relational systems, object-oriented systems – And different brands for each type – Why? History, needs and requirements

• Is there a standard? Yes, 2 really
– Relational DBMS – SQL as the access language » DDL, DML, etc. » Note: Can have SQL w/o relational...
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