Accounting information system an overview 9e bodnar hopwood chapter 12

File Processing and Data Management Concepts Chapter 12  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/Hopwood 12– Learning Objective Define the basic terms used in database technology  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/Hopwood 12 – Introductory Terminology Field Data items Attribute Elements These are used interchangeably to denote the smallest block of data that will be stored and retrieved  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/Hopwood 12 – Introductory Terminology A field may be a single character or number, or it may be composed of many characters or numbers Customer name Employee social security number Purchase order number Customer account number  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/Hopwood 12 – Introductory Terminology Logical grouping of fields are called records An employee A customer A vendor An invoice  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/Hopwood 12 – Data Occurrences A record occurrence is a specific set of data values for the record  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/Hopwood 12 – Data Occurrences For the record EMPLOYEE (NAME, NUMBER, AGE) we might have the occurrence EMPLOYEE (Brown, 111222333, 33)  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/Hopwood 12 – Fixed- and Variable-Length Records In a fixed-length record, both the number of fields and the length (character size) of each field are fixed In variable-length records, the width of the field can be adjusted to each data occurrence A trailer record is an extension of a master record  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/Hopwood 12 – Several Suppliers and Warehouses Example PART_NO PNAME TYPE COST PVEND – the name of the vendor or supplier WARHSE – where the part is stored LOC – the last two digits of the zip code  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/Hopwood 12 – One Storage Location Example PART (PART_NO, PNAME, TYPE, COST, PVEND #1, WARHSE #1, LOC#1, PVEND #2, WARHSE #2, LOC#2)  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/Hopwood 12 – Directly Accessed Files Direct-access files allow individual records to be almost instantly retrieved without the use of an index Each record is assigned to a storage location that bears some relationship to the record’s key values Most direct-access file systems convert a key to a storage location address  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/Hopwood 12 – Use of a Direct-Access File Data records Add remainder to displacement address (10) Randomizing computation (÷ 7) File storage area  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/Hopwood 12 – Use of a Direct-Access File Record Key 15 17 11 22 Remainder Displacement after factor + = Record division (initial address storage by seven of file area) address 10 11 10 13 10 14 10 11  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/Hopwood Overflow 12 – Use of a Direct-Access File Address 10 11 Range of 12 randomizing 13 computation 14 15 16 Storage allocated for 17 overflow 18 records Contents … Record KEY 15* … Record KEY 17 Record KEY 11 … … Record KEY 22 … Overflow indicator  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/Hopwood 12 – Economic Relations between File Organization Techniques The basic economics of file processing are largely determined by the activity ratio What is the activity ratio? It is the number of accessed records divided by the number of records in the file The second economic consideration concerns response time  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/Hopwood 12 – Economic Relations between File Organization Techniques What is response time? It is the length of time the user must wait for the system to complete an operation Response time is affected by the physical access time Another factor that can affect response time is how data records are physically distributed on the disk  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/Hopwood 12 – Learning Objectives and Explain the benefits of database management systems Describe the considerations that are appropriate to the design of computer-based files and databases  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/Hopwood 12 – Database Management Systems and Databases in Practice Database Management Systems (DBMS) are computer programs that enable a user to create and update files, to select and retrieve data, and to generate various outputs and reports All DBMS contain three common attributes for managing and organizing data  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/Hopwood 12 – Database Management Systems and Databases in Practice What are these attributes? Data description language (DDL) Data manipulation language (DML) Data query language (DQL)  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/Hopwood 12 – Why Database Management Systems are Needed DBMS integrate, standardize, and provide security for various accounting applications In the absence of integration, each type of accounting application such as sales, payroll, and receivables will maintain separate, independent data files and computer programs  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/Hopwood 12 – Database Management Concepts Application One X Y A B Application Two X Y C D  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/Hopwood 12 – Database Management Concepts X Y A B Database dictionary and access codes Database system Data manipulation routines X Y A D C D X Y A B Logical file Application one X Y C D Logical file Logical file Security screened inquiry file Application two 12 –  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/Hopwood Database Documentation and Administration Database dictionaries are used both alone and with DBMS to centralize, document, control, and coordinate the use of data within an organization The data dictionary is simply another file, sort of file of files, whose record occurrences consist of data item descriptions  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/Hopwood 12 – Data Dictionary Format Specifications  Name  Definition  Aliases Characteristics  Size  Range of values  Encoding  Editing data Utilization  Owner  Where used  Security code  Last update  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/Hopwood 12 – End of Chapter 12  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/Hopwood 12– 55 ... Publishing, Accounting Information Systems, 9/e, by Bodnar/ Hopwood 12 – Database Management Systems and Their Architecture Conceptual level Database contents Uses of database Desired reports Information. .. reviewed  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/ Hopwood 12 – Database Management Systems and Their Architecture Logical level Logical data structures:... Relational  2004 Prentice Hall Business Publishing, Accounting Information Systems, 9/e, by Bodnar/ Hopwood 12 – Database Management Systems and Their Architecture Physical level Access methods: