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1、Databases for Bioinformatics,陈艳炯 医学院免疫与病原生物学系,数据库系统基础,数据库的基本概念 数据管理系统的发展 数据库技术的发展 数据库系统的组成 数据库应用系统体系结构,数据(Data),数据的定义 描述客观事物(对象)的符号记录 数据的种类 文字、图形、图像、声音 数据的特点 数据与其语义是不可分的,数据概念的变化特点 质的规定：由简单到集成；由私有到共享。 量的刻化：由小量到大量到海量。 所处位置：在软件中的从属地位到主导地位。,信息(Information) 是以数据为载体的对客观世界实际存在的事物、事件和概念的抽象反应。 信息=数据+数据处理,Dat
2、a processing,Computer data processing is any process that uses a computer program to enter data and summarise, analyse or otherwise convert data into usable information. The process may be automated and run on a computer. It involves recording, analysing, sorting, summarising, calculating, dissemina
3、ting and storing data. Because data are most useful when well-presented and actually informative, data-processing systems are often referred to as information systems.,Data analysis When the domain from which the data are harvested is a science or an engineering, data processing and information syst
4、ems are considered too broad of terms and the more specialized term data analysis is typically used, focusing on the highly-specialized and highly-accurate algorithmic derivations and statistical calculations that are less often observed in the typical general business environment. Data analysis pac
5、kages like DAP, gretl or PSPP are often used.,Elements of data processing,In order to be processed by a computer, data needs first be converted into a machine readable format. Once data is in digital format, various procedures can be applied on the data to get useful information. Data processing may
6、 involve various processes, including: Data acquisition（数据采集） Data entry（数据录入） Data cleaning（数据清理） Data validation（数据验证） Data tabulation（数据制表） Statistical analysis（统计分析） Computer graphics（计算机图形） Data warehousing（数据存储） Data mining（数据挖掘）,Data acquisition,In computer data processing, data acquisition i
7、s the sampling of real world physical conditions and conversion of the resulting samples into digital numeric values that can be manipulated by a computer. The components of data acquisition systems include: Sensors that convert physical parameters to electrical signals. Signal conditioning circuitr
8、y to coerce sensor signals into a form that can be converted to digital values. Analog-to-digital converters, which convert conditioned sensor signals to digital values. Depending on the application, acquired data may be displayed, analyzed, or recorded, or some combination there of. Data acquisitio
9、n applications may be controlled by commercial DAQ software or by custom programs developed using various general purpose programming languages such as BASIC or C. Specialized programming languages used for data acquisition include EPICS for building large scale data acquisition systems, LabVIEW, wh
10、ich offers a graphical programming environment, and MATLAB which provides graphical tools and libraries for data acquisition and analysis.,Data cleansing or data scrubbing is the act of detecting and correcting (or removing) corrupt or inaccurate records from a record set, table, or database. Used m
11、ainly in databases, the term refers to identifying incomplete, incorrect, inaccurate, irrelevant etc. parts of the data and then replacing, modifying or deleting this dirty data. After cleansing, a data set will be consistent with other similar data sets in the system. The inconsistencies detected o
12、r removed may have been originally caused by different data dictionary definitions of similar entities in different stores, may have been caused by user entry errors, or may have been corrupted in transmission or storage. Data cleansing differs from data validation in that validation almost invariab
13、ly means data is rejected from the system at entry and is performed at entry time, rather than on batches of data. The actual process of data cleansing may involve removing typographical errors or validating and correcting values against a known list of entities. The validation may be strict (such a
14、s rejecting any address that does not have a valid postal code) or fuzzy (such as correcting records that partially match existing, known records).,A data entry clerk is a member of staff who reads hand-written or printed records and types them into a computer. They are sometimes employed on a tempo
15、rary basis, but most large companies which have large amounts of data will hire on a near-permanent basis.,In computer science, data validation is the process of ensuring that a program operates on clean, correct and useful data. It uses routines, often called validation rules or check routines, tha
16、t check for correctness, meaningfulness, and security of data that are input to the system. The rules may be implemented through the automated facilities of a data dictionary, or by the inclusion of explicit application program validation logic. Incorrect data validation can lead to data corruption or a security vulnerability. Data validation checks that data are valid, sensible, reasonable, and secure before they are processed.,Computer graphics are graphics created using computers and, more g
