Ch1/W2 Flashcards
database
organized collection of logically related data
data
unstructured and structed reresentation of objects and events that have meaning and importance
Info
data that has been processed to increase knowledge of the person who uses the data
metadata?
data about data!!!
data item: course
metadata: type, length, description, source, data defintions
JUST NOT LOCATION ON DISK
cons of traditional file processing systems like excel
6
- program-data dependance: The close relationship between data stored in files and the software programs that update and maintain those files. Any change in data organization or format requires a change in all the programs associated with those files.
- duplication
- limited sharing
- long dev tie: forced to start from scratch every time
- lots of maintenance
solution of traaditional processing systems?
DBMS
Data model
two types
graphical systems used to caputre the nature and relationships among data
- ent dm: high level ent and elaitonships for org
- project dm: more detailed view (matching data structure or data warehouse)
relational db
db that reps data as a collection of tables where relationships are reped by comm vals in related tables
DBMS
software system that enables use of database aproach
pros of db approach
- program data independance! data idescriptions are stored in the REPOSITORY. separate from application programs using the data
- planned redundnacy: redundancy only when helpful
- improved conssistency
- improved data sharing: db is designed as a shared user resources and several usr views allowed
- more productivity, beter standards, better quality of data
- improved data accesibility and responsiveness, reudced mmaitnenance, increased decision support
user viewq
a logical descirptiono of some portion of db that is reuqired by a user to perform a ta
constarnt
rule tat cant be violated by db users
costs and risks of db approach
1, new specialized personnel
2. installation and management cost
3. conversion costs
4. need for explciti backup and recovry
5. org conflict
9 elements of database envrionment
- Data modelling and design tools: sw tools that create data models (CENTRE LEFT)
- repository: Central base for all data (BOTTOM ELFt)
- DBMS: create maintian provide controlled access to user databases (CENTRE BOTTOM)
- Database: org collection of lofically related data (BOTTOM RIGHT)
- APP programs: CREATE and maintain DB (coomunicate info to users) (CENTRE RIGHT)
- UI: Centre middle
- Data and DB admin: top left- databse designers
- System devs: top centre- design applications
- End users: top right- users who add delete etc data
DB dev rpocess
- enterpreise data modelling (first step where the scope and general contents of org db is specified)
- implement SDLC:
a. Planning (ent modelling) for prelim understanding
b. Analysis (concepual data modelling):requirements analysis & structuring (THIS IS WHERE THE CONEPTUAL DATA MODEL IS CREATED!)
-> EVERY ATTRIBUTE IS DEFINED! EVERY CATEGORY OF DATA LISTED
c. Design (logical db design-> LOGICAL SCHEA, physical db design-> PHYSICAL SCHEMA)
-»>Logical: info requriements and structure
-»»Physical: develop tech an dorg specs
how is logical schema stored in secondary memory?
d. Implementation (DB imp) program test install
e. Maintenance: monitor repair enhance
PALPIM
ALTERNATIVE TO SDLC
rad methods, like prototypig (iterrative process of sd where requirements are converted to working system that is revised consistently)
agile software dev
approach to db focused on individuals an dinteractons over processes and tools
CONCEPTUAL
LOGICAL
PHYSICAL
DEFINE THESE SCEMAS
C: detailed tech ind specification of the overall structure of org data
L: rep of a db for particular dm tech
p: specs for how data is stored in computers secondary emmory
3 schemas
external: view of database users (comb of ent dms(top down) or detailed user views(bottom up)
conceptual: ERD MODELS
internal: logical and physical schema
business analysts: analyze the business situation and develop detailed system and program specifications for projects. *
Systems analysts: specify computer systems requirements
Database analysts and data modelers: determining the requirements and design for the database component of the information system.
Users: provide assessments of their information needs and monitor that the developed system meets their needs.
- Programmers: design and write computer programs that have commands to maintain and access data in the database embedded in them.
Database architects: These individuals establish standards for data in business units, striving to attain optimum data location, currency, and quality. *
Data administrators: ensure consistency and integrity across databases, and as experts on database technology, they provide consulting and training to other project team members.
Project managers : oversee assigned projects, including team composition, analysis, design, implementation, and support of projects.
typical functions of dbms
-> data storage managemet
-> manipulation mgmt
-> def services
storage mgmt: manages permanent storage of data
manipulation mgmt: can retrieve update and delte existing data
def services: accepts data definitons like external conceptual and internal schema
typical functions of dbms
-> dictionary/systems catalogue mgmt
-> db comm ints
-> auth/sec mgmt
dictionary catalog: description of data items are stored and are accessible
db comms: comm messages
auth: protects db against unauth access
typical functions of dbms
-> backup
-> concurrnecy
-> transaction
-> db access
backup: backup
concerrucn: consistent state of presenvation
transaction: idates abotu a transaction are made
access: access via swl
what are two compoennnts of a query language
data def language, data manipulation langugage
