Definition of database

A .Group of on file data in magnetic disk, optical disk or depositorer sekunder

B. Inwrought collection from data which each other [is] interconnected the than an enterprise ( company, governmental institution or private sector)

C. Manufacturing business of production planning Data, data produce the aktual, data of material ordering, hospital of patient Data, doctor, nurse.

B. DBMS(Database management system )

Combined Database with the application software being based on database

This application programe used to access and look after the database

Especial target of DBMS is provide an efficient and easy environment for the use of, withdrawal and depository of data and information

Bit,Byte,field

· Bit represent part of containing smallest data assess 0 or 1

· Byte Corps from bit which of a kind

· Field byte-byte which of a kind, in data bases used by a attribute term

Type-type atribut

· Single multivalue

o Single only can be filled by at most one value

o Multivalue can be filled with interest from one value with same type

· Atomic vs composition

o Indiscrete Atomic into smaller attribute

o Composition represent the merger from some smaller attribute

· Derived Attribute

o attribute which its value can be yielded from other;dissimilar attribute value, for example age yielded from attribute of date of delivering birth

· Null Value Attribute

o Attribute which do not own the value to a[n record

Mandatory Value Attribute

o Mandatory Value Attribute

Record

Representing an data line in an relationship

Consist of attribute corps of where the attribute interact to inform the entity / relationship completely

Key

• Superkey a set of one or more attributes which, taken collectively, allow us to identify uniquely an entity in the entity set.
• A superkey may contain extraneous attributes, and we are often interested in the smallest superkey. A superkey for which no subset is a superkey is called a candidate key.
• A primary key is a candidate key (there may be more than one) chosen by the DB designer to identify entities in an entity set.
• Alternate Key [is] attribute from candidate key which is not chosen become the primary key.
• Foreign Key represent any attribute subjecting to primary key [of] [at] other tables. Foreign Key will be became of by a[n relationship owning kardinalitas one to many ( one to a lot of) or many to many ( a lot of to a lot of). Foreign Key usually is always placed at tables aiming to a lot of.
• External key represent a[n lexical attribute ( or gathering of lexical attribute) what its values always identify.

ERD(Entity relation diagram)

ERD is an network model using wording kept in system in abstraction.

· Difference of between DFD and ERD.

o DFD represent a[n model of function network to be executed by system

ERD represent the model of data network emphasizing at structure and relationship data

ENTITY

ER of Diagram Entity depicted with the long form square. Rntity is something that there [is] in real system and also abstraction [of] where on file data or where there are data.

At ER of Diagram relationship can be depicted with a lozenged. Relationship [is] natural [relation/link] that happened [among/between] entitas. Generally called with the elementary vb. so that facilitate to doconduct the its relationship read.

Relationship Degree

is the number of entities participating in a relationship. Degree which is often used in the ERD.

Atribute

is the nature or characteristics of each entity and relationship

Cardinalitas

tupel indicates the maximum number that can be berelasi with entities on the other entity

Degree of relationship

1. Unary Relationship

model is the relationship between the entity originating from the same entity set.

2. Binary Relationship

model is the relationship between 2 entities.

3.Ternary Relationship

is a relationship between the instance of

Cardinalitas.

• Mapping Cardinalities: express the number of entities to which another entity can be associated via a relationship. For binary relationship sets between entity sets A and B, the mapping cardinality must be one of:
  1. One-to-one: An entity in A is associated with at most one entity in B, and an entity in B is associated with at most one entity in A.
  2. One-to-many: An entity in A is associated with any number in B. An entity in B is associated with at most one entity in A.
  3. Many-to-one: An entity in A is associated with at most one entity in B. An entity in B is associated with any number in A.
  4. Many-to-many: Entities in A and B are associated with any number from each other.

Notation

An E-R diagram express the overall logical structure of a database graphically.

· 1.) Use rectangles representing entity sets.

· 2.) Use ellipses representing attributes

· 3.) Use ellipses representing attributes.

· 4.) Use diamonds representing relationship sets.

· 5.) Use lines linking attributes to entity sets and entity sets to relationship sets

Colecctive entity

Atributte a as key

Colecctive relation

Link