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데이터베이스6

E-R model Designing a database → 전체적인 디자인 과정을 이해해보자. (교과서 읽으세염...) Initial phase characterize fully the data needs of the prospective database users Second phase choose a data model Apply the concepts of the chosen data model Translate the requirements into a conceptual schema of the database A fully developed conceptual schema indicated the functional requirements of the enterprise Describe the kinds of .. 2023. 10. 27.
Structured Query Language SQL data manipulation language (DML) SELECT, FROM, WHERE NULL values Set operations String operations, ordering Aggregate functions, aggregation → querying && modifying the databases Aggregate Functions - Having Clause groups뒤에 오는 HAVING과 groups 앞에 있는 HAVING이 다름. 두 개는 다른 쿼리이다. 왼쪽에 있는 것은 GROUP BY 를 한 instructor중에서 65000이 넘는 교수 오른쪽은 65000이 넘는 instructor를 찾아서 평균을 낸 것. 따라서 더 높음. More SQL Nested subq.. 2023. 10. 27.
MySQL과 명령어 Functinality Massive, Convenient, Multi-user, Safe, Efficient, Reliable safe; transaction Structured Query Language(SQL) SQL : Structured Query Language principal language describe and manipulate relational databases Very high-level c, java, basic보다 high level이다. what to do >> how to doo not specifying data-manipulation details DBMSs figure out the'best' way to execute queries query optimizatito.. 2023. 10. 27.
Relational Algebra Relational algebra Select Project Cartesian product Join Rename Union Set-intersection Set-difference Operands and Operators Operands: 변수나 값. (새로운 값을 구성할 수 있는) 3, a, 4, d Operators: 절차를 나타내는 기호 (지정된 operands에서 새 값을 구성하는) add, sub, mult, div Relational Algebra operations 들의 집합을 포함하는 절차적인 언어 하나 혹은 두개의 relations을 input으로 갖고 새로운 relation을 output으로 갖는다. Basic operaties Select, Project, Cartesian Prod.. 2023. 10. 26.
Database Systems 1. What is database? Motivation Database Organized collection of inter-related data that models some aspect of the real-world. Databases are one of the core components of most computer applications Database Examples Universities: Registration, grades Financial market credit card transactions Sales and purchases information of stocks and bonds Real-time market data Enterprise information Sales: c.. 2023. 10. 26.
Database Theory 당시에는 정말 나의 피땀을 갈아넣어 만든 정리 노트... 데이터베이스 정말 열심히 했었더랬다. ㅎ 데이터 베이스를 사용하는 방법 (how to work?) Data model Relational Data model → R - DBMS Relational algebra SQL: Structured Query Language SQL DML: SELECT, INSERT, UPDATE, DELETE, JOIN, WITH SQL DDL: CREATE. ALTER, DROP ER Diagram, NORMALIZATION Transaction Key, Constraints, Views Procedures, Functions, Trigger 데이터 베이스 내부 동작(how it works?) Transactions D.. 2022. 8. 4.

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