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Bi 1

Cc khi nim v

h qun tr CSDL(RDBMSRelational Database Management System)

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Mc tiu bi hc

Gii thch khi nim v d liu v CSDL. M t cch thc qun tr d liu. nh ngha h qun tr CSDL v danh sch cc tnh

nng. Phn bit cc m hnh CSDL. nh ngha v gii thch h qun tr CSDL - RDBMS. M t cc thc th, bng v lit k cc thuc tnh

ca bng. Lit k s khc bit gia DBMS v RDBMS.

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D liu (Data) v CSDL (Database)

D liu(data) c ngha l thng tin v n l thnh phnquantrngtrong btklnhvc,cng vicno.

MtCSDL (database) l mttphpcc dliu(data).

CSDL l mttphpdliuctchcsao cho nidung can c thddng truy cp,qunl v cpnht.

Database

Users

Cho php truy xutThng tin

Lu trThng tin

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Qun tr d liu Qun tr d liu ch vic qun l lng ln

thng tin bao gmcviclutrthng tin vcchthao tc trn cc thng tin .

Hai phngphp quntrdliukhc nhau: H thng qun l da trn tp tin (File-based

systems)

HthngCSDL (Database systems)

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H thng qun l tp tin 1-3Features of file-based systems:

Lu tr d liu trong cc tp tinring bit.

Mt nhm cc tp tin c lu trtrn my tnh v c truy cp bng

cc thao tc my tnh.

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V d:

CSDL ManagementStudent schanhngbngsau:

Student (StudNo, StudName, Age, Address, )

Class (ClassNo, ClassName, FacultName)

.

H thng qun l tp tin 2-3

SudentDatabase

Data entry and reports

File handling routines

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H thng qun l tp tin 3-3

Cc nhc im ca h thng:

Dthav khng nhtqun dliu

Truy vntxut C lpdliu

Truy cpngthibtthng

Vnbomt

Vnton vn

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H thng CSDL CSDL s dng lu tr d liu c h thng v c t

chc. Gip ngi dng qun l d liu nhanh chng vd dng

uimcahthngCSDL ny l:

Gimdthadliu

Trnh vnkhng nhtqun dliu

Dliuclutrc thcchia s

Cc chunc thcthitlpv duy tr

Tnh ton vndliucduy tr

Bomtdliuc thcthcthi

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H qun tr CSDL (Database ManagementSystem - DBMS) 1-2

RDBMS l mttpcc bnghi c lin quan vinhau vtpcc chngtrnh cho php truy xutv thao tc trncc bnghi .

RDBMS cung cpmtmi trngthuntinv hiuqukhi c mtlnglndliuv giao dchcxl.

RDBMS cho php ngisdngnhngha,tov duytr cc CSDL v cung cpcch thciukhintruy xutticc CSDL .

Cc h qun tr CSDL khc nhau h tr cc ngn ngtruy vn khc nhau mc d c mt ngn ng truy vnchuncgil SQL (Structured Query Language).

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H qun tr CSDL (Database ManagementSystem - DBMS) 2-2

Database

Data entry andreports

DBMS

Data entry andreports

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Li ch ca h qun tr CSDL Lutrdliu

nhnghadliu

Thao tc dliu

Bomtv ton vndliu

Truy cpngthiv phchidliu

Hiunngcao

iukhinatruy cp

Ngn ngtruy xutCSDL v giao din lptrnh ngdngAPI(Application Programming Interfaces)

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Cc m hnh CSDL 1-5

Cc CSDL c thkhc nhau davo mhnh v chcnngcadliu.

Mtm hnh d lium tkho chadliu (container) v x l vic lu tr vtruy xutdliutkho .

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Cc m hnh CSDL 2-5

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Cc m hnh CSDL 3-5 Cc kiukhc nhau cam hnh CSDL:

Flat-file Data model (M hnh Flat-file Data)

Trong m hnh ny CSDL ch cha mt bng haymtfile dliu.

Hierarchical Model (M hnh phn cp)

Cc bn ghi lin kt vi nhau thng qua cc cpbcgingnhcutrc cy.

Trong m hnh ny, cc quan hcgil quanhcha (parents)con (children). Mtbnghi chac th c 1 hocmtvi bnghi con nhngmtbnghi con chc 1 v ch1 bnghi cha.

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Cc m hnh CSDL 4-5 Network Data Model (M hnh mng)

Tng t nh m hnh phn cp. M hnh phn cp thc ra l tp con ca m hnh

mng. M hnh mng s dng l thuyt tp to ra mt

cy phn cp m trong mi nt con c th cnhiu hn mt nt cha.

D liu c lu tr trong cc tp thay v nh dngtheo cy phn cp. iu ny gii quyt c vn d tha d liu.

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Cc m hnh CSDL 5-5 Relational Data Model (M hnh quan h)

Tt c cc d liu c cha trong cc bng, ccbng cha cc dng v cc ct.

D liu trn hai bng c quan h vi nhau thngqua cc ct.

Nhng php ton c cung cp thc hin trncc dng ca bng d liu.

Trong m hnh ny m t CSDL l mt tp hp ccquan h. Mt dng c gi l Tupe, mt ct cgi l thuc tnh v bng c gi l quan h. Danhsch cc gi tr c th c ca mt trng c gi lmin.

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Relational Database Management System (RDBMS)

RDBMS l mthquntrCSDL m ttcdliucnhn thybingidng ctchchon ton bngcc bngdliuv ttccc thao tc CSDL lm victrn bng.

MtCSDL quan hl mtCSDL cchia thnh nhngnvlogicgil bngv cc bngc quan hvinhau.

TABLE 1Key

Data...

TABLE 2Key

Data...

Relationship

Database

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Nhng thut ng lin quan tiRDBMS

Nhng thut ng thng dng trong RDBMS: D liu (Data) c biu din nh mt tp cc

quan h. Mi mt relation c biu din bng mt table. Columns l cc thuc tnh. Rows (tuples) biu din cc thc th. Mi bng c cc tp thuc tnh gi l key: nh

danh duy nht mi thc th.

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Nhng thut ng lin quan tiRDBMS

Thut ng nghaRelation Mt bng (table)Tuple Mt hng hoc mt bn ghi trong bng

Attribute Mt trng hoc mt ct trong bng

Cardinality of a relation S hng trong bng

Degree of a relation The number of attributes in a relation

Domain of an attribute The set of all values that can be taken by the attribute

Primary Key of arelation

An attribute or a combination of attributes that uniquelydefines each tuple in a relation

Foreign Key An attribute or a combination of attributes in one relationR1, which indicates the relationship of R1 with anotherrelation R2

The foreign key attributes in R1 must contain valuesmatching with those of the values in R2

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RDBMS Users

Many users are involved in thedesign, use, and maintenance of alarge database:

Database Administrator (DBA)

Database Designer

System Analysts and

Application Programmers

DBMS Designers and Implementers

End User

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Entities (Thc th) v Tables Mt thc th l mtngi,mtv tr, mtvt,

mtitng,mtskinhocthmch mtlthuytcnhnbitr rng.

Mithcthc cc ctnh cbitnnhl thuctnh v cttn ph hp

Mtbnggmmtnhm cc thc thc quanhvinhau cgil mttpthcth.

Thut ng thc th v bng thng c thay th nhau. Mt bng cng c gi lrelation, hng c bitnnh l tupes vcc ctchiul cc thuctnh.

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Entities v Tables

Emp_No Emp_Name Emp_DOB Emp_DOJ

345 James 24-Sep-1968 30-May-1990

873 Pamela 27-Jul-1970 19-Nov-1993

693 Allan 10-Sep-1970 01-Jul-1992

305 Geoff 12-Feb-1973 29-Oct-1996

Attributes

EMPLOYEE

Table

Tuple

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S khc bit gia DBMS v RDBMS

DBMS RDBMS

It doest not need to have data in atabular structure nor does it enforcetabular relationships between data

items.

In RDBMS, tabular structure is a mustand table relationships are enforced bythe system. These relationships enable

the user to apply and manage businessrules with minimal coding.

Small amount of data can be storedand retrieved.

RDBMS can store and retrieve largeamount of data.

DBMS is less secure than RDBMS. RDBMS is more secure than DBMS.

It is a single user system. It is a multiuser system.

Most DBMSs do not supportingclient/server architecture.

It supports client/server architecture.