Post on 30-Jan-2016
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Roots of the Database System: File System
Problems with File System Data Management
Database System
File
System1
Case of a File A manager of any small
organization was able to keep track of necessary data using a manual file system.
A MANUAL FILE SYSTEM consist mainly of a collection of file folders, properly tagged(or labeled) and kept in a filing cabinet.
Manager’s File Cabinet
Technical:Data pertaining
to only those people whose
duties were properly
classified as TECHNICAL.
Doing well for a while
At first, data collection was relatively small and an organization’s manager had few reporting requirements, the manual system served its role well as a data storehouse.
But the organization grew… However, as the organization
grew and the storing requirements became more complex, keeping track of the data became more difficulty.
Retrieval was time consuming and cumbersome, thus, it is unlikely that the data could generate useful information.
Consider these questions: How many products sold during
the past week, month, quarter or year?
What is the current daily, weekly, quarterly or yearly sales peso volume?
Did we gain more this month compared to last month’s sales?
The Data Processing Specialist Thus, the manager needs to hire a
new kind of professional: a Data Processing (DP) Specialist.
The task is to be able to manage and process data. Process means to draw out useful information from the data.
The DP creates file structures, the software and design reports from the data.
Customers
Alfred Ramos
Phone: 0927-565-4896Address: #42 Rodeo St. Macabalan, CDOZIP: 9000
Agent Name: Leah VidalPhone: 0927-565-4444Insurance Type: T1Amount: P500.00Renewal Date: December 12, 2012
Customer FileC_NAME C_PHNE C_ADD C_ZIP A_NAME A_PHONE TP AMT REN
Alfred Ramos
0927-595-784 CDO 9000 Leah Vidal 0927-565-4444
T1 500.00 Dec 12, 2012
Jordan Belen
0928-594-5979 CDO 9000 Jasmin Trio 0927-332-1322
T1 100.00 Dec 15, 2012
RebeccaDuran
0917-449-459 DVO 8000 Leah Vidal 0927-565-4444
A1 250.00 Mar 2, 2012
Jose Reyes
0922-465-4465 DVO 8000 Jasmin Trio 00927-332-1322
T2 210.00 Mar 5, 2012
Dorothy Villafria
0927-466-7999 ILOILO 6800 Richard Silva 0922-526-4466
A2 100.00 Jan 3, 2013
Marco Mercedes
0922-965-1221 CBU 6000 Leah Vidal 0927-565-4444
T2 150.00 Jun 7, 2013
Kurt Cobaltito
0927-465-4652 ILOILO 6800 Leah Vidal 0927-565-4444
A1 200.00 Mar 29, 2012
Sophia Mendez
0927-465-4465 CEBU 6000 Richard Silva 0922-526-4466
A1 200.00 Apr 8,2013
Dominic Fuetlaki
0928-446-4656 ILIGAN 9200 Leah Vidal 0927-565-4444
T2 100.00 May 4, 2012
Consider these questions: How many agents do we
have? Sales per agent?
Singular File System
Each department has their own file system.
It is not the concern of the Customer’s Department.
The Customer’s Department must create their own file system.
CUSTOMER FILECUSTOMER FILE SALES FILESALES FILE
File Mgmt
Program
File Mgmt
Program
File Report
Program
File Report
Program
File Mgmt
Program
File Mgmt
Program
AGENT FILEAGENT FILE
File Report
Program
File Report
Program
FILESTRUCTUREFILESTRUCTURE
FILE SYSTEM PROGRAM
FILE SYSTEM PROGRAM
Problems with File System Data Management2
Task of a Filing System
Storing DataSaving and Organizing
Updating Data (Edit or Delete)
Retrieving DataProcessing Data to Reports
File Systems are inefficient with the three task
1. Data Retrieval Task 3GL Languages vs 4GL Languages 3 GL :
BASIC,C++, Fortran,CobolProgrammer to specify what must be done and how it
is to be done
4 GL :SQLProgrammers to specify what must be done without
specifying how it must be done.Save an average of 60% of lines of code
3GL vs 4GL3GL 4GL
DO WHILE NOT (EOF)Read CUSTOMERIF CUSTOMER.C_ZIP = “36123”
THEN PRINT C_NAME, C_PHONE, C_ZIP
ENDDO;
SELECT C_NAME,C_PHONE,C_ZIPFROM CUSTOMERWHERE CUSTOMER.C_ZIP=‘36123’;
1. It requires extensive programming2. There is no ad hoc query capabilities3. System Administration can be complex and difficulty4. It is difficult to make changes to existing structure5. Security features are likely to be inadequate
2. Data Storing and Organizing STRUCTURAL Structural Dependence: If the file
structure changes, the file system program must adapt.
Structural Independence: the file system program need not to change if the file structure changes
DATA Data Dependence: Data access
programs are subject to change when any of the file’s data storage characteristics change.
Data Independence: possible to make changes in the data storage characteristics without affecting the application program’s ability to access data.
2. Data Updating
Data RedundancyPremise: data should be accurate (no data
inconsistencies) and verifiable (always yield consistent results)
Data anomalies – develops when all of the required changes in the redundant data are not made successfulUpdate Anomalies – not all are updatedInsertion Anomalies Deletion anomalies -
Database Systems3
What is a DATABASE?
The database is consist of logically related data stored in a single logical data storeroom or repository.
Employees File System
Customers
SalesInventory
Accounting Department
Hardware Software People Procedures Structures