Field, data types, key field/primary key, secondary key

Field:
Definition:An {ordered set} of {fields}, usually stored contiguously.  The term is used with similar meaning in several different contexts.  In a file, a "record" probably has some fixed length, in contrast to a "line" which may have any length and is terminated by some {End Of Line} sequence).  A {database} record is also called a "row".  In a {spreadsheet} it is always called a "row".  Some programming languages use the term to mean a type composed of fields of several other types ({C} calls this a "{struct}"). In all these cases, a record represents an entity with certain field values. Fields may be of a fixed width ({bit}s or {characters}) or they may be separated by a {delimiter} character, often {comma} ({CSV}) or {HT} ({TSV}). In a database the list of values of a given field from all records is called a column. (2002-03-22).
http://www.learnthat.com/define/view.asp?id=6799
Example:, a single VSAM file stores both employee and address records. The correct record interpretation is managed by associating the value of a record type field with a record layout. The following COBOL definition shows how a REDEFINES clause specifies an alternate record type for ADDRESS-INFORMATION. If RECORD-TYPE = "A" Classic Data Architect uses the layout for address data.

01  EMPLOYEE-ADDRESS-RECORD.
    05 EMP-ID            PIC X(6).
    05 RECORD-TYPE       PIC X.
       88 RECORD-IS-EMPLOYEE   VALUE 'E'.
       88 RECORD-IS-ADDRESS    VALUE 'A'.
    05 EMPLOYEE-INFORMATION.
       10 LAST-NAME      PIC X(20).
       10 FIRST-NAME     PIC X(20).
       10 DATE-OF-BIRTH  PIC 9(8).
       10 MONTHLY-SALARY PIC S9(5)V99 COMP-3.
       10 FILLER         PIC X(48).
    05 ADDRESS-INFORMATION REDEFINES EMPLOYEE-INFORMATION.
       10 ADDRESS-LINE-1 PIC X(30).
       10 ADDRESS-LINE-2 PIC X(30).
       10 ADDRESS-CITY   PIC X(20).
       10 ADDRESS-STATE  PIC XX.
       10 ADDRESS-ZIP    PIC 9(5).

 Picture:

        http://freepages.genealogy.rootsweb.ancestry.com/~donegalstrongs/ire_db.gif

Data Types:
Definition: The description of the kinds of data stored, passed and used.
http://www.ois.com/Products/glossary-of-terms.html#d

Example and Picture:

Qualitative vs Quantitative DataTopic Index | Algebra Index | Regents Exam Prep Center Examine the differences between qualitative and quantitative data. Qualitative Data Quantitative Data Overview: Deals with descriptions. Data can be observed but not measured. Colors, textures, smells, tastes, appearance, beauty, etc. Qualitative → Quality Overview: Deals with numbers. Data which can be measured. Length, height, area, volume, weight, speed, time, temperature, humidity, sound levels, cost, members, ages, etc. Quantitative → Quantity  Example 1: Oil Painting Qualitative data: blue/green color, gold frame smells old and musty texture shows brush strokes of oil paint peaceful scene of the country masterful brush strokes Example 1: Oil Painting Quantitative data: picture is 10" by 14" with frame 14" by 18" weighs 8.5 pounds surface area of painting is 140 sq. in. cost $300 Example 2: Latte Qualitative data: robust aroma frothy appearance strong taste burgundy cup Example 2: Latte Quantitative data: 12 ounces of latte serving temperature 150º F. serving cup 7 inches in height cost $4.95 Example 3: Freshman Class Qualitative data: friendly demeanors civic minded environmentalists positive school spirit Example 3: Freshman Class Quantitative data: 672 students 394 girls, 278 boys 68% on honor roll 150 students accelerated in mathematics Topic Index | Algebra Index | Regents Exam Prep Center Created by Donna Roberts Copyright 1998-2010 http://regentsprep.org Oswego City School District Regents Exam Prep Center http://www.regentsprep.org/Regents/math/ALGEBRA/AD1/qualquant.htm Key field:  Definition:  A field in a segment or record that holds the value of a key to that record.  http://www.answers.com/topic/key-fieldPrimary Key:   Definition:The primary key of a relational table uniquely identifies each record in the table. It can either be a normal attribute that is guaranteed to be unique (such as Social Security Number in a table with no more than one record per person) or it can be generated by the DBMS (such as a globally unique identifier, or GUID, in Microsoft SQL Server). Primary keys may consist of a single attribute or multiple attributes in combination.    Example:Imagine we have a STUDENTS table that contains a record for each student at a university. The student's unique student ID number would be a good choice for a primary key in the STUDENTS table. The student's first and last name would not be a good choice, as there is always the chance that more than one student might have the same name.    http://databases.about.com/cs/administration/g/primarykey.htmPicture:   http://www.fgcu.edu/support/office2007/access/Images/PrimaryKey.gif Secondary Key:    Definition:A key that holds the physical location of a record or a portion of a record in a file or database, and provides an alternative means of accessing data. Also known as alternate key.    http://www.answers.com/topic/secondary-key