Data types databases
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DATA TYPES, DATABASES. Gergely ZAJZON Dr. Med. DATABASE. Simply:structured collection of data. DATABASE. Simply:structured collection of data. DATABASE. Simply:structured collection of data Storage: a collection of tables connecting to each other. DATABASE.

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Data types databases

DATA TYPES, DATABASES

Gergely ZAJZON Dr. Med.


Database

DATABASE

  • Simply:structured collection of data


Database1

DATABASE

  • Simply:structured collection of data


Database2

DATABASE

  • Simply:structured collection of data

  • Storage: a collection of tables connecting to each other


Database3

DATABASE

  • In computer science, a database is a structured collection of records or data that is stored in a computer system so that a computer program or person using a query language can consult it to answer queries.

  • The records retrieved in answer to queries are information that can be used to make decisions.


Data types databases

DATA

  • Data is visualised form of some kind of knowledge. Representative property of somebody or something.

  • From IT perspective: data is coded information, stored in a computer as a signal sequence.

  • Has to be stored in a structured and processable form


Data examples

DATA - examples

  • PATIENT DATA:- name- birth date

    - address

    - „TAJ” – patient code

    Phone book:- name- address- phone number


Information

INFORMATION

  • The Sesame Street character Cookie Monster describes information as "news or facts about something."

  • Measure unit of information:

    bit: value can be 1 or 0 (true / false).

  • Information is the result of processing, gathering, manipulating and organizing data in a way that adds to the knowledge of the receiver..


Information1

INFORMATION

Why do we create databases?

  • Storing and searching of data

  • Retrieval of new informations from stored data collections


Data types

DATA TYPES

  • Basic property of data fields

  • Defines:

    • a set of values

    • structure of data

    • allowable operations on those values

  • Makes it possible, that in one column of a table only same type of data can be stored.


Basic data types

BASIC DATA TYPES

  • Can not be divided to further separete parts


Countable data type classess

COUNTABLE DATA TYPE CLASSESS


Real data type classess numeric real data types

REAL DATA TYPE CLASSESSNumeric real data types


Data type

DATA TYPE

  • Choosing the correct data type:

    • Helps making your database more structured

    • Eg.: a field containing birth dates should be DATE type.

    • Helps validating your data:

    • Eg.: DATE field can not contain a date like 31. february 2008.

    • You can not enter a text into an INTEGER field


Data types1

Data Types

  • Binary

    • Database specific binary objects

    • Pictures, digital signatures, etc.

  • Boolean

    • True/False values

  • Character

    • Fixed width or variable size

  • Numeric

    • Integer, Real (floating decimal point), Money

  • Temporal

    • Time, Date, Timestamp


Spreadsheet database

SPREADSHEET <-> DATABASE

  • Spreadsheet (EXCEL table): structured.- search- order- filter

  • Software: Eg.: MS-Excel


Spreadsheet database1

SPREADSHEET <-> DATABASE

  • „Excel database”: table with special layout:

  • Rows of the table are connected with eachoter, containing the properties of one selected object. Columns: containing the same kind of property for each object. The table has a header in the first row.


Spreadsheet database2

SPREADSHEET <-> DATABASE


Spreadsheet database3

SPREADSHEET <-> DATABASE

  • Disadvantages of Spreadsheet

  • The same data set can only be modified by one user at the same time

  • Storage of data is not safe enough

  • Structure of data and connections are not defined


Spreadsheet database4

SPREADSHEET <-> DATABASE

  • Disadvantages of Spreadsheet

  • Logical limit: can not use multiple tables easiliy, as connections between tables can not be defined


Spreadsheet database5

SPREADSHEET <-> DATABASE

INDIRECT PROPERTY => REDUNDANCY, MISTAKES IN DATA INPUT


Database4

DATABASE

  • Data collection organized on the basis of a data model.

  • Contains:

    • data

    • Structure of data

    • Connection rule descriptions


Data model

DATA MODEL

  • A logical structure, defining the layou of the stored data.

  • Contains no data values.

  • Only properties of data, structure and possible connections


Data model1

DATA MODEL

CONCEPTUAL DATA MODEL:

  • Analysis of the informations and connections between them.

  • Independent from software tools

    PHYSICAL DATA MODEL:

  • Structured used in the database:definition of tables, data types, connection

  • Software dependent


Data types databases

CONCEPTUAL DATA MODEL

MOZIK

FILMEK

PK

PK

MOZI_ID

FILM_ID

M

N

MOZINEV

FILMCIM

MOZICIM

HOSSZ

MOZITEL

NYELV

MOZIWEB

RENDEZO


Data types databases

PHYSICAL DATA MODEL

MOZI__FILM

FILMEK

MOZIK

PK

MOZIFILM_ID

PK

N

FILM_ID

MOZI_FK

PK

MOZI_ID

N

1

FILMCIM

1

FILM_FK

MOZINEV

HOSSZ

MOZICIM

VETITES

NYELV

MOZITEL

RENDEZO

MOZIWEB


Parts of a database

Parts of a database

  • Attributes (fields)

    • An attribute or field is a component of a record that describes something about an item.

  • Records

    • A record is the representation of an individual item.

  • Table

    • A collection of records

  • Database

    • A collection of tables and rules for accessing the tables


Parts of a database1

Parts of a database

Record

Tables

Attribute/Field

  • Records become “rows”

  • Attributes/fields become “columns”

  • Rules determine the relationship between the tables and tie the data together to form a database


Referential integrity

Referential Integrity

  • Rules to preserve relationships

  • Prevents orphan records

    • Cannot add records on many sides

    • Cannot delete from one side

  • Cascade update

  • Cascade delete


Normal forms

NORMAL FORMS

  • The normal forms (abbrev. NF) of relational database theory provide criteria for determining a table's degree of vulnerability to logical inconsistencies and anomalies. The higher the normal form applicable to a table, the less vulnerable it is to such inconsistencies and anomalies. Each table has a "highest normal form" (HNF): by definition, a table always meets the requirements of its HNF and of all normal forms lower than its HNF; also by definition, a table fails to meet the requirements of any normal form higher than its HNF.

  • The normal forms are applicable to individual tables; to say that an entire database is in normal form n is to say that all of its tables are in normal form n.


Normalizing

Normalizing

  • Dependencies between data are identified

  • Redundant data is minimized

  • Reduces chances of data errors

  • Reduces disk space

  • The data model is flexible and easier to maintain


First normal form

First Normal Form

  • Eliminate repeating columns in each table

  • Create a separate table for each set of related data

  • Identify each set of related data with a primary key

Benefits: Now we can have infinite phone numbers or company addresses for each contact.

Drawback: Now we have to type in everything over and over again. This leads to inconsistency, redundancy and wasting space. Thus, the second normal form…


Second normal form

Second Normal Form

  • Create separate tables for sets of values that apply to multiple records

  • Relate these tables with a “foreign key”.


Third normal form

Third Normal Form

  • Eliminate fields that do not depend on the primary key.

Is this enough? Codd thought so…

What about “many to many”?


Kinds of relationships

Kinds of Relationships

  • “One to One”

    • One row of a table matches exactly to another

      • One person, one id number, one address

  • “One to Many”

    • One row of a table matches many of another

      • One person, many phone numbers

  • “Many to Many”

    • One row may match many of another or many rows match one row of another


Data types databases

BETEGEK

PK

TAJ

NEV

IRSZ

VAROS

CIM

HAZIORVOS

REND IRSZ

REND VAROS

REND_CIM

RENDMH_TEL

BETEGEK

ORVOSOK

PK

PK

TAJ

PECSÉT

M

N

NEV

ORVOS

IRSZ

IRSZ

VAROS

VAROS

CIM

CIM

TEL


Data management language

DATA MANAGEMENT LANGUAGE

  • SQL = Structured Query Language

  • DDL – Data Definition (CREATE)

  • DML – Data Manipulation (INSERT, UPDATE, DELETE)

  • QL – Query Language (SELECT)


Table types

TABLE TYPES

  • Main (core) tables

  • Subtables

  • Linking tables (association table)

  • Dictionary tables (look-up table, value list)


Database server

DATABASE SERVER

  • A database server is a computer program that provides database services to other computer programs or computers, as defined by the client-servermodel. The term may also refer to a computer dedicated to running such a program. Database management systems frequently provide database server functionality, and some DBMS's (e.g., MySQL) rely exclusively on the client-server model for database access.

  • Database Master servers are central and main locations of data while Database Slave servers are synchronized backups of the master acting as proxies.


Database server1

DATABASE SERVER

  • Special DBMS software

  • user interface is not an important aim

  • Allows multi-user change access

  • Controll of user rights

  • Backup of stored data

  • Transaction management


Database servers

DATABASE SERVERS

  • Oracle

  • MS-SQL

  • My-SQL

  • PostgreSQL


Data types databases

Gergely Zajzon Dr. Med.

E-mail:[email protected]

Web:http://www.gyogyszerugy.hu

Telefon:+36-20-9604294


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