Collecting and organizing information
ENTITY
Thing about which you gather information
(rectangle)

RELATIONSHIP
Connection between entities
Has information about the entities that are a part of it
(diamond)

ENTITIES:
STUDENT
	IDnumber	Name Address Phone etc….
CLASS
Discipline	CourseNumber Title
SECTION
	Discipline 	CourseNumber Code Semester Time Place 
INSTRUCTOR
	FIDnumber Name Address Phone etc….

RELATIONSHIPS:
IS	(not needed as a separate table)
	Discipline 	CourseNumber Code Semester	
ENROLL
	IDnumber Discipline 	CourseNumber Code Semester
T
	FIDnumber Discipline 	CourseNumber Code Semester

TERMS:	
KEY
	The attribute(s) that uniquely identify an entity
Alternate Key
	Something that could have been used as the key
Foreign key
	A key for  different table
TUPLE
	The elements in a row; information about a single entity
DETERMINES
	(a.k.a. functional determinacy)
	Given the KEY, the attribute is fixed
	(The KEY ALWAYS determines the non-key attributes)
One to Many
	ONE class can have MANY sections
	ONE section CANNOT have many classes
	(Put the KEY of the ONE in the table of the MANY;
	Might not need a relationship table)
Many to Many
	One student can have many sections
	One section can have many students
Few to Many
	(e.g. team teaching)
	One of just a few to many

IMPORTANT:
	Each piece of information only appears ONCE
	(except for key/identifiers)
	(normally, keys/identifiers do not change, and are only used to identify)
	Example:
		A student changed her name
		She had to go to EVERY OFFICE in the college to report the name change
		NOW a student name is only stored in ONE spot
		So changing a name is (fairly) easy
Normalization:
	Rules to make it easier to use a database

	FIRST:
Each (non-id) data/attribute only appears ONCE in the database
Only ONE piece of information can be in each field
	(only have one name, one phone, one address…..)
	NO repeating groups
	SECOND:
	No attribute is determined by PART of the key
	THIRD:
	No attribute is dependent on something that depends on the key
	(no attribute is transitively dependent on the key)