Database Introduction History Why we want to use them Other fun Copyright © 1998-2016 by Curt Hill

Six Generations of Data Management Manual – Prehistory Punch cards – 1900 Programmed Unit record – 1955 Online database – 1965 Client Server, Relational – 1980 Multimedia – 1995 All of these still continue Data Management: Past, Present, and Future, by Jim Gray Microsoft Research, Technical Report MSR–TR–96-18 Copyright © 1998-2016 by Curt Hill

Copyright © 1998-2016 by Curt Hill Manual Writing has existed for millennia Kings used writing to inventory their goods, record their laws Sumerian tablets date from 2000 BC or before Copyright © 1998-2016 by Curt Hill

Copyright © 1998-2016 by Curt Hill Punch cards Originally used by Jacquard to program silk weaving machines Not really data management Hollerith used to record census data in 1890 A suite of machines that would punch, sort, print and tabulate from cards Programmed by rewiring control panels Known as unit record or electronic accounting machines Copyright © 1998-2016 by Curt Hill

Copyright © 1998-2016 by Curt Hill Machines Copyright © 1998-2016 by Curt Hill

Programmed Unit record Stored program computers change the face of data management Tapes store the data much more densely than cards Programming removes the limits on what sort of calculations or transformations may be done on the data Produced a file-oriented record processing approach Copyright © 1998-2016 by Curt Hill

Copyright © 1998-2016 by Curt Hill Consider an example A college has many files that describe their system Faculty Catalog or courses Grades Students Among many others We will look at payroll and grades as an example Copyright © 1998-2016 by Curt Hill

Copyright © 1998-2016 by Curt Hill Payroll File Fields Name Address Salary/wage Earnings Year to Date Among very many more Copyright © 1998-2016 by Curt Hill

Copyright © 1998-2016 by Curt Hill Payroll File Copyright © 1998-2016 by Curt Hill

Copyright © 1998-2016 by Curt Hill Grades Fields Course Including section Student name Term Letter grade Instructor Copyright © 1998-2016 by Curt Hill

Copyright © 1998-2016 by Curt Hill Grades File Copyright © 1998-2016 by Curt Hill

Background Vocabulary fields collection of related characters records collection of related fields files collection of related records database collection of related files Copyright © 1998-2016 by Curt Hill

Copyright © 1998-2016 by Curt Hill How to use Actions we might want on each file: Create Update (add, remove, change records) Sort Generate any of several reports Each action for each file would be a program for an overworked programming staff Typically a COBOL program Eight programs, or sections of programs, for two files These are typically done in a batch environment Copyright © 1998-2016 by Curt Hill

Copyright © 1998-2016 by Curt Hill First Database? Integrated Data Store (IDS) appears to be the first DBMS Architect is Charles Bachman 1973 Turing award winner First ran in 1963 on GE hardware It was a network database Not originally online, since there was no Internet Later connected to Teletypes for updating inventory Copyright © 1998-2016 by Curt Hill

Copyright © 1998-2016 by Curt Hill IDS Capabilities Single interface between application programs and the data Maintained metadata on the data Data independence Schemas can be changed without changing applications Implemented a buffer manager Restricted form of ACID Later implemented a backup and recovery system Copyright © 1998-2016 by Curt Hill

Copyright © 1998-2016 by Curt Hill Online database Many things do not work well in batch mode: Travel reservations need up to the second information The database is born Started out as disk based unit record, but that is not the best organization for this type of application Developed into two models: Hierarchical and network Copyright © 1998-2016 by Curt Hill

Copyright © 1998-2016 by Curt Hill Two Models Both require direct access devices Each requires disk addresses in the database Required to get to the pointed at record directly Programmer as navigator Access programs must still be written specially for a particular database Must understand the low level structure Must run on the same machine as database Copyright © 1998-2016 by Curt Hill

Client Server, Relational EF Codd suggests the relational model and he and other develop a substantial theoretical base Queries may now be simple and short Needs to know a schema, but not complete organization This allows transmission of a simple query Client server computing is born Copyright © 1998-2016 by Curt Hill

Relational Database The key The solution All the programs previously described are about the same – every update is nearly the same All that changes is the underlying file The solution Describe the file in a general way Generate a program that handles the file based on the description Copyright © 1998-2016 by Curt Hill

How to describe a file A file is a collection of records Each record is a collection of fields Typically only one type of record in a file Each field is described by a: Name Type For example numeric, string, boolean etc. Length Booleans have a predefined length, others require specification Copyright © 1998-2016 by Curt Hill

Copyright © 1998-2016 by Curt Hill SQL Structured Query Language Has become the “standard” for queries A relational database does not have to accept SQL Unless it wants to be commercially viable SQL is mostly declarative but with some procedural features Declarative – what is wanted Procedural – how to get it Copyright © 1998-2016 by Curt Hill

Copyright © 1998-2016 by Curt Hill The Files Copyright © 1998-2016 by Curt Hill

What is wrong with the original example? Redundancy in faculty description Space is wasted Discrepancies may occur between grades and payroll Some reports need to access multiple files Eg. Transcript generation Complicates the programming issue Copyright © 1998-2016 by Curt Hill

Advantages (1 of 3) Data independence Efficient access Application program no longer need some or all of the files Do not know or care how data is stored, aka abstraction Simplifies application development Efficient access The DBMS employs sophisticated access techniques seldom used by normal programmers Copyright © 1998-2016 by Curt Hill

Advantages (2 of 3) Integrity constraints Security The DBMS may check data in a way seldom done in normal file processing Eg. Account validity Security A DBMS may enforce requirements on who can access the data and in what way Copyright © 1998-2016 by Curt Hill

Advantages (3 of 3) Administration Concurrent access Minimize redundancy Manage sharing of the data Optimize for the enterprise, not a small group Easier to backup the data Concurrent access Manages the simultaneous update problem Copyright © 1998-2016 by Curt Hill

Disadvantages A DBMS is: Complex Expensive Bulky Simple file access is much quicker and less expensive The view a DBMS provides may not be helpful to a particular application Copyright © 1998-2016 by Curt Hill

Copyright © 1998-2016 by Curt Hill Multimedia The relational model was king for a time What if what we to store does not conform to the notion of typed text? Sound, pictures, video One of the results is the object oriented data base which stores data as objects Data and programs to manipulate Copyright © 1998-2016 by Curt Hill

Copyright © 1998-2016 by Curt Hill NoSQL Once it is realized that the relational database is not the end-all, all manner of new types of databases appear These are the NoSQL databases SQL is the universal query language NoSQL may mean no SQL or Not Only SQL This is a field that is not finished developing Copyright © 1998-2016 by Curt Hill

Copyright © 1998-2016 by Curt Hill Finally The course focuses on relational data bases They are comparatively standardized We will also examine the NoSQL databases and the Hierarchical and Network models Of course, we will also learn SQL Copyright © 1998-2016 by Curt Hill