Quiz 6

DATABASE AND ER-DIAGRAM

DEFINITION OF DATABASE:

- A set of file data in magnetic disk, optical disk or other secondary storage.
- Collection of integrated data-related data of an enterprise (company,government or private).
for example:
Company data = manufacturing production planning, actual production data, data ordering materials, etc.
Hospital = patient data, doctor, nurse, etc.


DATABASE MANAGEMENT SYSTEM
-colection of database with the application software being based on database.
- program aplication is use to acess and protec database.
-the purpose of DBMs is prepare easy and efficiency to use data storage and information.

BIT, BYTE, FIELD

- Bit is small part of data that contains the value 0 or 1
- Byte is a set of bits similar
- Field is a set of byte-byte similar, in the database is called attribute.


ATRIBUT/FIELD
- Is a characteristic from an entity that provides detail explanation about these entity.
- A relationship have atributes,
for example : student :student number,name,address
Car :nomor_plat,colour,type,cc

ATTRIBUTE TYPE
1. Single vs multivalue

- Single
-> Single can be filled only one value.
- Multivalue
-> Can be filled with more than one value with the similar.

2. Atomic vs composition
- Atomic
-> Atomic can’t divided into smaller atribute.
- Composite
-> Is a composite from some smaller etribute.

3.Derived Attribute
- the atribute that value can be derived from other atribute value, for example age that derived from the atibute date of birth.

4.Null Value Attribute
- Atribut is not value to a record.

5.Mandatory Value Attribute
- Attributes must have values.

RECORD/TUPLE
Is a line of data in a relationship
Consists of a set atributes where the atributes make a relation to informing entity or relation completely



ENTITY/FILE
- File is collection from similar records and have same element, same atribute but different dat values

Type of file
- In the process of application, file can categories are:
1. Master File
2. Transaction File
3. File Report
4. File History
5. File Protection
6. File Work


DOMAIN

- Domain is a set of values that allowed into one or more atribute. Each atribute in one relational database is defined as a domain.


LOCK THE DATA ELEMENT

- Key is elements of record that used to find record in access time or used to identify each entityor record or line


SPECIES OF KEY

- Super Key
Superkey is one or more atribute from a table that can be used to identify entity or record from the table uniquely (not all of atribute become superkey)

- Candidate Key
Is superkey with minimal atribute. Candidate Key can not fill atribute from other table so that Candidate Key exactly Super Key

- Primary Key
One of the other atribute from Candidate Keycan be found as a PK with three categories are:
- Key is more natural to use as reference
- Key is more simple
- Key is guaranteed unique

- Alternate Key
Alternate Key is atribute from Candidate Key that not choosen as Primary Key

- Foreign Key
Foreign Key is any atribute that point to PK in other table. Foreign Key will be happened in a relation that have cardinality one to many or many to many. Foreign Key always located in table that aim to many.

- External Key
External key is a lexical atribute ( set lexical atribute) that its values always idetify one intance object.


ERD (ENTITY RELATIONSHIP DIAGRAM)

- ERD is model of function network that use word order that saved in abstract system.
- Differences between DFD and ERD
> DFD is model function network that will be done by system
> ERD is model data network that emphasize in structure and data relationship



ELEMENT ERD

- Entity
> In ER D E is described in rectangle. Entity is something in the real system and in abstract where the data stored.

- Relationship
> In ER D relationship can be described with belah ketupat. R is natural relation that happened between entity. Generally, the name is given to the verb base making easier to read the relations

- Relationship Degree
> Is number of entity that partisipate in one relationship. Degree that is often used in ERD.

- Attribute
> Is characteristic from each entity and relationship.

- Kardinalitas
> Indicate the number maximal tupel that relate to other entity.



RELATIONSHIP DEGREE

->>>Unary Relationship
Model relationship between entity come from same model relationship entity set.

->>>Binary Relationship
Model relationship between 2 entities.

->>>Ternary Relationship
Is relationship between instance from 3 type entities unilateraly.


KARDINALITAS

There are 3 kardinalitas relations, namely;
- One to one
-> Level one to one relationship with the one stated in the entity's first event, only had one relationship with one incident in which the two entities and vice versa.
- one to many or many to one
->Level one to many or many to one relationship is the same as the one to many depending on the direction from which the relationship is viewed. For one incident in the first entity can have many relationships with the incident on the second entity, if the one incident in which two entities can have only one incident hubugan with the first entity.
- many to many
-> Level many to many if each event in entity have more relationship with other entity event

EXEMPLARY KARDINALITAS


NOTATION (E-R DIAGRAM)

Symbolic notation in the ER diagram is:
- Rectangle represent the collective entity
- Circle represent the attributes
- Rhomb represent collective relationships
- Line as the set of relations between the Association and the