DB7 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. Handshaking with an R-DBMS Introduction to MySQL MySQK is an SQL-based relational database management system(DBMS) Free and open-source Owned by Oracle Commercial version of MySQL Compatible with standard SQL Frequently used for commercial web services Why Mysql? Popular active discussion all over the Internet Versatile runs on Linux, Windows, MacOS, Solaris, FreeBSD Cost starts from zero High performance(fast and reliabl.. 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. 이전 1 2 다음
