data types, databases
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
DATA TYPES, DATABASES
Gergely ZAJZON Dr. Med.
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DATABASE
• Simply: structured collection of data
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DATABASE
• Simply: structured collection of data
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DATABASE
• Simply: structured collection of data
• Storage: a collection of tables connecting to each other
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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.
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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
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DATA - examples
• PATIENT DATA:- name- birth date- address- „TAJ” – patient code
Phone book:- name- address- phone number
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INFORMATION
• 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..
• The Sesame Street character Cookie Monster describes information as "news or facts about something."
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INFORMATION
Why do we create databases?
• Storing and searching of data
• Retrieval of new informations from stored data collections
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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.
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BASIC DATA TYPES
• Can not be divided to further separete parts
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COUNTABLE DATA TYPE CLASSESSNUMERIC
Byte 0-255 8 bit
Shortint (-128)-127 8 bit
Integer (-32768)-32767 16 bit
LOGICAL 1 or 0 1 bit
CHARACTER Any characters 1 byte (8 bit)
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REAL DATA TYPE CLASSESSNumeric real data types
Real (-2,9*10-39)-(1,7*1038) 48 bit
Single (-1,5*10-45)-(3,4*1038) 32 bit
Double (-5*10-324)-(1,7*10308) 64 bit
Extended (-3,4*10-4932)-(1,1*104932)
80 bit
Comp -2-63 + 1..263-1 64 bit
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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
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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
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SPREADSHEET <-> DATABASE
• Spreadsheet (EXCEL table): structured.- search- order- filter
• Software: Eg.: MS-Excel
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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.
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SPREADSHEET <-> DATABASE
TAJ Name Address Birth date.: Phone number:
123456789 Iv Béla Bp. 1014 Palota utca 1
1235.12.20. 06-1-2020030
234567890 Könyves Kálmán
IV. kerület Mély utca 3
1308.Jan.1 +36-20-1234567
345678901 Harmadik András
Székesfehérvár 8000 Fő út 4.
1290-04-01 (30) 1234567
456789012 Dobzse László
Bp. 1031 Kis utca 3 1492.Március 2 2345678
012345678 Kalapos József
Bp. 1220 Nagy utca 1
30/04/1835 06201234321
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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
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SPREADSHEET <-> DATABASE
• Disadvantages of Spreadsheet
- Logical limit: can not use multiple tables easiliy, as connections between tables can not be defined
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SPREADSHEET <-> DATABASE
Name Postal code
City Address Doctor Off_PC
Office_city Off_address Office_phone
Balla Béla 2080 Érd Fő u. 3. Dr. House 1191 Budapest Kék u. 3. 405-2039
Kis Péter 1022 Budapest Kis u. 2. Dr. Green 1221 Budapest Fa u. 5. 373-8022
Nagy Irén 1134 Budapest Új u. 4. Dr. House 1191 Budapest Kék u. 3. 303-1048
Pók Géza 2560 Diósd Tár u. 9. Dr. Kovac 2205 Diósd Zár u. 10. 323-581
INDIRECT PROPERTY => REDUNDANCY, MISTAKES IN DATA INPUT
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DATABASE
• Data collection organized on the basis of a data model.
• Contains:– data– Structure of data– Connection rule descriptions
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DATA MODEL
• A logical structure, defining the layou of the stored data.
• Contains no data values.
• Only properties of data, structure and possible connections
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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
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CONCEPTUAL DATA MODEL
MOZIK
MOZI_ID
MOZICIM
MOZITEL
MOZIWEB
MOZINEVM
FILMEK
FILM_ID
HOSSZ
NYELV
RENDEZO
FILMCIM
PKN
PK
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PHYSICAL DATA MODEL
MOZIK
MOZI_ID
MOZICIM
MOZITEL
MOZIWEB
MOZINEV1
FILMEK
FILM_ID
HOSSZ
NYELV
RENDEZO
FILMCIM
PK
1PK
MOZI__FILM
MOZIFILM_ID
FILM_FK
VETITES
MOZI_FK
PKN
N
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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
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Parts of a database
Record
Attribute/Field
Tables
• Records become “rows”• Attributes/fields become “columns”• Rules determine the relationship between the tables and tie the data together to form a database
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Referential Integrity
• Rules to preserve relationships
• Prevents orphan records– Cannot add records on many sides– Cannot delete from one side
• Cascade update
• Cascade delete
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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.
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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
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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
ContactsId Name Company Address Phone ZipCode
1 Joe ABC 123 5532 12345
1 Joe ABC 123 2234 12345
1 Joe ABC 123 3211 12345
2 Jane XYZ 456 3421 14454
3 Chris PDQ 789 2341 14423
3 Chris PDQ 789 6655 14423
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…
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Second Normal Form
• Create separate tables for sets of values that apply to multiple records
• Relate these tables with a “foreign key”.
People
Id Name Company Address Zip
1 Joe ABC 123 12345
2 Jane XYZ 456 14454
3 Chris PDQ 789 14423
PhoneNumbers
PhoneID Id Phone
1 1 5532
2 1 2234
3 1 3211
4 2 3421
5 3 2341
6 3 6655
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Third Normal Form
• Eliminate fields that do not depend on the primary key.
People
Id Name AddressID
1 Joe 1
2 Jane 2
3 Chris 3
Address
AddressID Company Address Zip
1 ABC 123 12345
2 XYZ 456 14454
3 PDQ 789 14423
PhoneNumbers
PhoneID Id Phone
1 1 5532
2 1 2234
3 1 3211
4 2 3421
5 3 2341
6 3 6655 Is this enough? Codd thought so…What about “many to many”?
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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
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TAJ Név Irsz Város Cím Háziorvos Rend_irsz Rend_város Rend_cím RendMh_tel
123456789 Balla Béla 2080 Érd Fő u. 3. Dr. Ház 1191 Budapest Kék u. 3. 405-2039
123456790 Kis Péter 1022 Budapest Kis u. 2. Dr. Zöld 1221 Budapest Fa u. 5. 373-8022
123456791 Nagy Irén 1134 Budapest Új u. 4. Dr. Ház 1191 Budapest Kék u. 3. 303-1048
123456792 Pók Géza 2560 Diósd Tár u. 9. Dr. Kovács 2205 Diósd Zár u. 10. 323-5819
TAJ Név Irsz Város Cím Háziorvos
123456789
Balla Béla
2080
Érd Fő u. 3.
Dr. Ház
123456790
Kis Péter
1022
Budapest
Kis u. 2.
Dr. Zöld
123456791
Nagy Irén
1134
Budapest
Új u. 4.
Dr. Ház
123456792
Pók Géza
2560
Diósd Tár u. 9.
Dr. Kovács
Háziorvos Rend_irsz
Rend_város
Rend_cím
RendMh_tel
Dr. Ház 1191 Budapest Kék u. 3. 405-2039
Dr. Zöld 1221 Budapest Fa u. 5. 373-8022
Dr. Ház 1191 Budapest Kék u. 3. 303-1048
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BETEGEK
TAJ
IRSZ
VAROS
CIM
NEV
PK
HAZIORVOS
REND IRSZ
REND VAROS
REND_CIM
RENDMH_TEL
BETEGEK
TAJ
IRSZ
VAROS
CIM
NEVM
ORVOSOK
PECSÉT
IRSZ
VAROS
TEL
ORVOS
PKN
PK
CIM
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DATA MANAGEMENT LANGUAGE
• SQL = Structured Query Language
• DDL – Data Definition (CREATE)
• DML – Data Manipulation (INSERT, UPDATE, DELETE)
• QL – Query Language (SELECT)
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TABLE TYPES
• Main (core) tables
• Subtables
• Linking tables (association table)
• Dictionary tables (look-up table, value list)
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DATABASE SERVER
• A database server is a computer program that provides database services to other computer programs or computers, as defined by the client-server model. 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.
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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
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DATABASE SERVERS
• Oracle
• MS-SQL
• My-SQL
• PostgreSQL
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Gergely Zajzon Dr. Med.
E-mail: [email protected]
Web: http://www.gyogyszerugy.hu
Telefon: +36-20-9604294