O) FILE ORGANIZATION For Example iled Student's name Record Number Name Course Date Grade A 9525012 Zhang MIS19989A recor Yan file Number Name Course Date Grade 9525012 Zhang MIS1998.9 Yan 9525018 Jeff Yu MIS 1998.9 9525027 He Hui MIS19989
HUANG Lihua, Fudan University FILE ORGANIZATION For Example, • Filed: Student’s name; • Record: Number Name Course Date Grade 9525012 Zhang Yan A MIS 1998.9 A record •File: Number Name Course Date Grade 9525012 Zhang Yan MIS 1998.9 A 9525018 Jeff Yu MIS 1998.9 A 9525027 … He Hui … MIS … 1998.9 … B …
FILE ORGANIZATION: Another way of thinking about database components ENTITY: Person, Place, Thing, Event about Which Data Must be Kept( a record describes an entity ATTRIBUTE: Description of a particular ENTITY corresponds to fields) KEY FIELD: Field Used to retrieve Update, Sort RECORD
HUANG Lihua, Fudan University FILE ORGANIZATION : Another way of thinking about database components—— • ENTITY: Person, Place, Thing, Event about Which Data Must be Kept ( a record describes an entity ) • ATTRIBUTE: Description of a Particular ENTITY （corresponds to fields) • KEY FIELD: Field Used to Retrieve, Update, Sort RECORD *
FILE ORGANIZATION Record ey Field Key field Attribute FDUNO. HKU NO NAME SEX TEL(O) TEL(H) 98HM001 93835 Xie Mingqiang M 58702331 98HM00293840 Yu Bing 65110968 98hm00393841 Wang pei F587110063568504 23306 98HM00493842 Ge ruijin M5693886056873143 98HM00593843 Wang Xintao M5861182865352394 98HM00693844 Fu Qiang F586606058836304 -6007
HUANG Lihua, Fudan University FILE ORGANIZATION FDU NO. HKU NO. NAME SEX TEL(O) TEL(H) 98HM001 93835 Xie Mingqiang M 58702331 98HM002 93840 Yu Bing F 65110968 98hm003 93841 Wang Pei F 58711001 -23306 63568504 98HM004 93842 Ge Ruijin M 56938860 56873143 98HM005 93843 Wang Xintao M 58611828 65352394 98HM006 93844 Fu Qiang F 58666060 -6007 58836304 Attribute Record Key Field Key Field File
KEY FIELD · Field in each record Uniquely Identifies THIS Record For RETRIEVAL UPDATING SORTING
HUANG Lihua, Fudan University KEY FIELD • Field in Each Record • Uniquely Identifies THIS Record • For RETRIEVAL UPDATING SORTING *
OD))Accessing Records from computer Files: Sequential vs. Direct or random file organization SEQUENTIAL: Data records must be retrieved in the same physical sequence in which they are stored. (Magnetic tape DIRECT Data can be accessed without regard to physical sequence. Disk) Direct file Sequential file p organization organization
HUANG Lihua, Fudan University Accessing Records from Computer Files:Sequential vs. Direct or random file organization • SEQUENTIAL: Data records must be retrieved in the same physical sequence in which they are stored. (Magnetic tape ) • DIRECT: Data can be accessed without regard to physical sequence. (Disk) * Direct file organization Sequential file organization