Presentation on theme: "DATA TYPES, DATABASES Gergely ZAJZON Dr. Med.. 2 DATABASE Simply:structured collection of data."— Presentation transcript:
DATA TYPES, DATABASES Gergely ZAJZON Dr. Med.
2 DATABASE Simply:structured collection of data
7 DATABASE Simply:structured collection of data
8 DATABASE Simply:structured collection of data Storage: a collection of tables connecting to each other
9 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. structured The records retrieved in answer to queries are information that can be used to make decisions.information
10 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
11 DATA - examples PATIENT DATA: - name - birth date - address - „TAJ” – patient code Phone book: - name - address - phone number
12 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..dataknowledge The Sesame Street character Cookie Monster describes information as "news or facts about something."Sesame Street Cookie Monster
13 INFORMATION Why do we create databases? Storing and searching of data Retrieval of new informations from stored data collections
14 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.
15 BASIC DATA TYPES Can not be divided to further separete parts
16 COUNTABLE DATA TYPE CLASSESS NUMERIC Byte bit Shortint(-128)-1278 bit Integer(-32768) bit LOGICAL1 or 01 bit CHARACTERAny characters1 byte (8 bit)
17 REAL DATA TYPE CLASSESS Numeric real data types Real(-2,9* )-(1,7*10 38 )48 bit Single(-1,5* )-(3,4*10 38 )32 bit Double(-5* )-(1,7* )64 bit Extended(-3,4* )- (1,1* ) 80 bit Comp bit
18 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 –You can not enter a text into an INTEGER field
20 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
22 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.
23 SPREADSHEET DATABASE TAJNameAddressBirth date.:Phone number: Iv BélaBp Palota utca Könyves Kálmán IV. kerület Mély utca Jan Harmadi k András Székesfehérvár 8000 Fő út (30) Dobzse László Bp Kis utca Március Kalapos József Bp Nagy utca 1 30/04/
24 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
25 SPREADSHEET DATABASE Disadvantages of Spreadsheet -Logical limit: can not use multiple tables easiliy, as connections between tables can not be defined
26 SPREADSHEET DATABASE NamePostal code CityAddressDoctorOff_P C Office_cityOff_addressOffice_phone Balla Béla2080ÉrdFő u. 3.Dr. House1191BudapestKék u Kis Péter1022BudapestKis u. 2.Dr. Green1221BudapestFa u Nagy Irén1134BudapestÚj u. 4.Dr. House1191BudapestKék u Pók Géza2560DiósdTár u. 9.Dr. Kovac2205DiósdZár u INDIRECT PROPERTY => REDUNDANCY, MISTAKES IN DATA INPUT
32 DATABASE Data collection organized on the basis of a data model. Contains: – data –Structure of data –Connection rule descriptions
33 DATA MODEL A logical structure, defining the layou of the stored data. Contains no data values. Only properties of data, structure and possible connections
34 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
35 CONCEPTUAL DATA MODEL MOZIK MOZI_ID MOZICIM MOZITEL MOZIWEB MOZINEV M FILMEK FILM_ID HOSSZ NYELV RENDEZO FILMCIM PK N
36 PHYSICAL DATA MODEL MOZIK MOZI_ID MOZICIM MOZITEL MOZIWEB MOZINEV 1 FILMEK FILM_ID HOSSZ NYELV RENDEZO FILMCIM PK 1 MOZI__FILM MOZIFILM_ID FILM_FK VETITES MOZI_FK PK N N
37 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
38 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
39 Referential Integrity Rules to preserve relationships Prevents orphan records –Cannot add records on many sides –Cannot delete from one side Cascade update Cascade delete
40 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.
41 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
42 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 Contacts IdNameCompanyAddressPhoneZipCode 1JoeABC JoeABC JoeABC JaneXYZ ChrisPDQ ChrisPDQ 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…
43 Second Normal Form Create separate tables for sets of values that apply to multiple records Relate these tables with a “foreign key”. People IdNameCompanyAddressZip 1JoeABC JaneXYZ ChrisPDQ PhoneNumbers PhoneIDIdPhone
44 Third Normal Form Eliminate fields that do not depend on the primary key. People IdNameAddressID 1Joe1 2Jane2 3Chris3 Address AddressIDCompanyAddressZip 1ABC XYZ PDQ PhoneNumbers PhoneIDIdPhone Is this enough? Codd thought so… What about “many to many”?
45 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
46 TAJNévIrszVárosCímHáziorvosRend_irszRend_városRend_címRendMh_tel Balla Béla2080ÉrdFő u. 3.Dr. Ház1191BudapestKék u Kis Péter1022BudapestKis u. 2.Dr. Zöld1221BudapestFa u Nagy Irén1134BudapestÚj u. 4.Dr. Ház1191BudapestKék u Pók Géza2560DiósdTár u. 9.Dr. Kovács2205DiósdZár u TAJNévIrszVárosCímHáziorvo s Balla Béla ÉrdFő u. 3. Dr. Ház Kis Péter Budape st Kis u. 2. Dr. Zöld Nagy Irén Budape st Új u. 4. Dr. Ház Pók Géza DiósdTár u. 9. Dr. Kovács HáziorvosRend_ir sz Rend_vár os Rend_cí m RendMh_t el Dr. Ház1191BudapestKék u Dr. Zöld1221BudapestFa u Dr. Ház1191BudapestKék u
47 BETEGEK TAJ IRSZ VAROS CIM NEV PK HAZIORVOS REND IRSZ REND VAROS REND_CIM RENDMH_TEL BETEGEK TAJ IRSZ VAROS CIM NEV M ORVOSOK PECSÉT IRSZ VAROS TEL ORVOS PK N CIM
48 DATA MANAGEMENT LANGUAGE SQL = Structured Query Language DDL – Data Definition (CREATE) DML – Data Manipulation (INSERT, UPDATE, DELETE) QL – Query Language (SELECT)
49 TABLE TYPES Main (core) tables Subtables Linking tables (association table) Dictionary tables (look-up table, value list)
50 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.computer program database computersclient-servermodelDatabase management systemsDBMS'sMySQL Database Master servers are central and main locations of data while Database Slave servers are synchronized backups of the master acting as proxies.
51 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