[SQL] ERD - Conceptual Data Modeling ๐Ÿ“–

์€์ง€ยท2023๋…„ 6์›” 26์ผ

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Systems Development Life Cycle

Planning โ–ถ Analysis โ–ถ Logical Design โ–ถ Physical Design โ–ถ Implementation โ–ถ Maintenance

Analysis : What the system should do, darwing the 'entity-relationship diagram'

Conceptual Data Modeling

Conceptual Data Modeling is ' ๋น„์ฆˆ๋‹ˆ์Šค ๊ทœ์น™์„ ์ •ํ•˜๊ณ , ์–ด๋–ค ๋ฐ์ดํ„ฐ๋ฅผ ๋‹ค๋ฃฐ ๊ฒƒ ์ธ์ง€ ์ปจ์…‰์„ ์ •ํ•˜๋Š” ๊ฒƒ'

โ–ผ ์ด๋ฅผ ์œ„ํ•œ ํ•˜๋‚˜์˜ ๋„๊ตฌ, ERD(Entity Relationship diagram)

ERD, Entity Relationship diagram

3 Components : Entities, Relationships, Attributes

ERD Construct, Entity

Entity

: ๋‹ด๊ณ ์ž ํ•˜๋Š” ๋ฐ์ดํ„ฐ
ect. ํ•™์ƒ, ์ˆ˜์—…, ๊ฐ•์˜์ž

Entity type

: ๊ณตํ†ต๋œ ํŠน์„ฑ์„ ๊ณต์œ ํ•˜๊ณ  ์žˆ๋Š” Entity์˜ ๋ชจ์Œ
โ–ท Relation or Table๊ณผ ๋งค์นญ๋˜๋Š” ๊ฐœ๋…

Entity instance

: ํ•˜๋‚˜์˜ ๋ฐœ์ƒ๋œ ์‚ฌ๊ฑด
โ–ท Row or Record์™€ ๋งค์นญ๋˜๋Š” ๊ฐœ๋…

ERD Symbols by Basic Crow's Foot

Entity types

Strong : ๋…๋ฆฝ์ ์œผ๋กœ ์žˆ์„ ์ˆ˜ ์žˆ์Œ
โ–ท Use 'single line'

Week : strong entity์— ์˜์กด, ํ˜ผ์ž์„œ ์žˆ์„ ์ˆ˜ ์—†์Œ.
โ–ท Only have a 'Partial identifier'
โ–ท entity box, partial identifier have 'double line'

Associative : Relaionship์•ˆ์— ์ƒ์„ฑ๋œ Entity
โ–ท Entity์˜ Relaionship์•ˆ์— ํฌํ•จ ๋œ Entity
โ–ท Use '๋‘ฅ๊ทผ ๋ชจ์„œ๋ฆฌ ์‚ฌ๊ฐํ˜•'

Attributes

Identifier : Single line

Partial idnetifier : Double line

Optional : Standard

Derived : [Derived]
โ–ท ๊ฐ’์ด ๋ณ€ํ™”ํ•˜๋Š” (ect. ๊ทผ์†๋…„์ˆ˜, ๋‚˜์ด)

Multivalued : {Multivalued}
โ–ท ๋ณต์ˆ˜์˜ ๊ฐ’

Composite : (, , ,)
โ–ท ์—ฌ๋Ÿฌ ๊ฐœ๋กœ ๊ตฌ์„ฑ๋œ ๊ฐ’

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