LA283 Section 2
			        dBASE III Lecture 1
				  March 28 and April 2


1. Readings
     -Go to Database Management Systems in the 283 class page
      	-click on *local documentation*
	-Peruse the sample programs and database files
		cartoon.dbf and cartoon.prg
		classic.dbf and classic.prg
    
2. What is a database?
     -organized collection of related data (information)
     -collection of data organized in a manner that allows access, retrieval,
      and use of that data
     -collection of information you can search or otherwise manipulate
     -enables an individual to store and track large sets of data

   Database Management System (DBMS)
     -software that helps you organize data in a way that allows fast and easy
      access to the information
     -reduced storage redundancy (data may not have to be stored in multiple
      places)
     -centralized security
     -integrated files-->relational structure allows different files (data tables)
      to be joined together; the DBMS stores information about how the
      files are related


			Popular DBMSs

                    dBase III+
                    dBase IV (DOS-based)
                    dBase V (DOS and Windows-based)
                    Paradox (DOS and Windows-based)
                    MS-Access (Windows-based)
                    MS-FoxPro (Windows-based)

3. Important terms for dBase III+

     command line  versus menu interface (Assist)


record:    all the data in any given row
           i.e., a single student
   
field:     the smallest unit of information for a record (attributes)
           i.e., course, grade, name, etc

field name: arbitrary name
            up to 10 characters and underscore (_)
            no spaces allowed
            must begin with a letter
            ex. Name,  Phone_Num

field type: the type of data

Character field:  contains descriptive data such as names, addresses, phone numbers,
                  etc) (maximum = 254 bytes)

Numeric field:    contains numbers used for calculations; must specify the number
                  of decimal places  (maximum = 19 bytes)

Date field:       automatically limited to 8 characters including / separators 
                  example: 02/21/74

Logical field:    limited to single characters; used to keep track of T/F conditions 
                  (maximum = 1 byte)

Memo field:       free form notes related to a record; keep notes on a record
                  (maximum = 5000 bytes)                                         

                                   
data base field structure:  a structure describing the field name, type, and width 


**** related fields are stored together as records
**** related records are stored together as files
**** related files are stored together as a database 



4. Steps to design and create a database

   A. Planning is most crucial element in the design phase of the database
   B. Understand the goal of the database
               -What will the data base look like?
               -What are the end user requirements?
               -Make sure all of the necessary data elements are included
   C. The Steps
               -design the structure of the dbf
               -create the structure
               -enter the data
               
5. Useful commands
	set default to a: (drive name)
   	create a:\dbf_name
	dir
   	display structure
   	modify structure
	

   	display
   	list        

   	browse 
   	append

	clear all
   	use 
   
   	use (dbf name)


	count
	count for test < 60
	average
	average for major = 'econ'