note in inglese su alcuni aspetti informatici: database, network, sql, world wide web. Riassunto sul Database, network, sql (2 pagine formato doc)
DATABASE, NETWORK, SQL: RIASSUNTO INGLESE
Database is a structured collection of records stored in computer system.Database use the specific software to organize data and to enable user to extract the desired information. DBMS stand for database management system, they are tree types of database models: hierarchical model, network model and relational model. In relational model are used tree key terms: relations, attributes and domains; relation is table with columns and rows, the named of the relation are called attributes and the domains is the values to take attributes.
SQL means Structured Query Language, is a database computer language for retrieval and management data in a relational database. SQL are used for creation and modification database schema.
DATABASE RIASSUNTO IN INGLESE
A network is two or more computers connected. There are two types of network: LAN and WAN; LAN are used in a restricted area, WAN use in wide area. The main components of a LAN are: workstation, file server, connection hardware and peripherals. There are tree topologies in a LAN: BUS, RING an STAR; BUS is a linear circuit and is easy to install but have low performance, RING is a close circuit and not depended from a central computer but if a node in the ring break down the transmission in the network fail, STAR has a central hub and have a greet performance but is very expensive to install because of the length of cabling.
Hyperlink is a electronic connection to allow user a easy access to information. URL means Uniform Resource Locator it’s an online address. HTTP is a protocol used to communication between server and client.
DATABASE IN INGLESE
Inter services are supported by the internet, e-mail, web, FTP, Usenet and Telnet. E-mail is a electronic message sent from a user to another via computer, e-mail are composed to account name at domain. FTP means File Transfer Protocol, this protocol are used to transfer files from one computer to another pc with a specific software. Usenet allow automatic distribution of global message. Telnet are used to log –in to the remote computer.
To test a program there are two strategies: bottom-up testing and top-down testing. Bottom-up test module individually which are then combined into larger units and finally tested with; top-down tested the whole program with individual modules replaced by stubs which may a message about the procedure. A good testing is important because it provides more information about the program and errors may be found before running the program.