AIS Chapter 2

online file update

The master file can be updated either in batch mode or online mode. The records in master file that are affected by the transaction are not updated instantaneously. Although, data entry occurs online as transactions occur, the relevant master files are updated only in batch mode whenever file maintenance run occurs. In this option too the master file is organized sequentially

batch file update

The master file can only be updated in batch mode. The transaction file must undergo the data preparation step of sorting and editing. The transaction file must be sorted in order of the primary key of the master file.

BLOBS

"binary large objects" field format that is used to store pictures, graphics, and other multimedia type

database

A group of logically related files that stores data and the associations among them.

comparison between batch and online update

Advantages of batch update: -more efficient use of computer system and personnel when transactions occur sporadically -more control over input and processing of transactions Advantages of online update: -master file always up to date -no separate data preparation step required, no need to sort transactions -faster access to master file data because of the use of magnetic disks for storage

law of requisite variety

Business control systems typically involve man and machines under man control. Ideally, for each way a system can get out of control, the control system provides for a corresponding control state - called this. The ability to adhere strictly to this is almost impossible.

Knowledge

Created when the right information is delivered at the right time and interpreted in the right manner. This can turn into wisdom and/or power.

Data to power value chain (information value chain)

Data -->Information-->Knowledge-->Wisdom-->Power

Field formats

Determines how data will be displayed, and is usually irreversible. Most computer systems support the following field formats: -numeric -text -currency -date/time -boolean -counter -BLOBS

text

Field format that can store any keyboard character. All characters (numeric and non-numeric) in the character set for a computer are called alphanumeric

relevance

Pertains to information's ability to assist a user in making a decision. Information must be received in a timely manner and must have the capacity to change the users decision.

reliability

Pertains to information's accuracy and freedom from errors. Control mechanisms should be in place to prevent errors in an information system. A closely related concept is reproducibility.

guidelines

These are suggestions for designing coding schemes: -use numbers instead of letters whenever possible (easier to enter into system) -allow for future expansion -make code as simple as possible

True

True or False: In effect, the counter becomes the system generated primary key for the file.

False - useless facts

True or False: The information system processes data to render important facts into useful information

True

True or False: The purpose of an information system is to convert data into information

False - can be

True or False: data cannot be input instantaneously, as it is generated, or subsequently at some predetermined point in time

True

True or False: if batch data input is employed, then the master file can only be updated in batch mode. That is the file maintenance run takes place at predetermined intervals such as at the end of the day.

True

True or False: For information to be truly useful and meaningful to a user, it must meet certain qualities - relevance and reliable.

Reproducibility

Using the same data as an input, and applying the same processing methods, another information system should generate identical information.

mnemonic code

a coding system in which letters are used either entirely or in part. Rather than using numbers, letters can be used to represent an item. Digit Position Represented Value 1 Position M=Manger S=Salesman A=Accountant 2-3 EE Number 01-99

Block coding

a coding system in which ranges of numbers are reserved for each category of the item being coded. The advantage is that the type of account can be discerned simply by knowing the account number. Position ! Range ----------!--------- Manager! 001-100 Accntant! 101-200 Purch Ag! 201-300 Salesman!301-400 ...

group coding

a coding system where each digit or group of digits in the code for an item signifies a different aspect of that item. Can be very flexible since there is no theoretical limit on the length of the code and the number of dimensions that can be used. Both letters and numbers can be used. Digit Position Represented Value 1 Position 1=Manger 2=Salesman 3=Accountant 2-3 EE Number 01-99

history files

a file type that are old transaction and master files that are maintained only for reference purposes and legal reasons only.

transaction file

a file type that contain relatively temporary information and are analogous to journals in a manual accounting system. Used to temporarily hold information until the information can be used to update the master files. Typically accessed to provide answers to a variety of questions posed by users at all levels in the organization.

Master file

a file type that contains relatively permanent information and are analogous to ledgers in a manual accounting system.

byte

a group of eight bits. It is roughly equivalent to a character, such as a letter or a number that is the lowest element understandable by humans

file

a group of logical records. All employee records together would create this.

field

a group of related bytes. A group of bytes would then form a word and make up the name of this.

record

a group of related fields. A group of fields make an employee record consisting of name, position, department, hire date, salary

primary key

a key that has the field or set of fields that uniquely identify records in a file. In most files it is obvious, it is possible for a file to have more than one unique identifier. Only one of the unique identifier can be the primary key

data processing cycle

a process that all information system applications undergo, a sequence of steps from data input to information output. Uses temporary data in the transaction file to update the permanent data in a master file and also generate relevant reports. Steps include: 1. data input 2. data preparation - used partially depending on whether the processing system is batch or online 3. data processing 4. file maintenance 5. information output

data processing

a step in the data processing cycle that includes all the calculations, comparisons, and manipulations that are undertaken in the particular application. Takes a transaction file as input and may access a reference file.

data input

a step in the data processing cycle that involves the collection of data and converting it into computer readable form. Results in the creation of the transaction file.

Data Preparation

a step in the data processing cycle that may need to facilitate data processing and file maintenance. Entails two steps: (1) validating - input data to filter out erroneous transactions (2) sorting - input data to facilitate the process of updating the master file. If the file processing method calls for master files to be updated instantly rather than periodically, then the sorting step would not be needed

information output

a step in the data processing cycle where reports are generated and output on paper or computer. Reports can either be routine scheduled reports that are always generated, demand reports that are generated only if specifically requested, or ad hoc reports that are designed to answer specific user questions.

File maintenance

a step in the data processing cycle where the master file is actually updated using the transaction file data. There are three file maintenance activities: 1. add - adding new master file records 2. update - modifying an existing master file record 3. delete - deleting an existing master file record

indexed file organization

a style of file organization that involves the creation of an ideax that contains key values and associated storage locations of the records in a file. Facilitates both sequential and random access. Often referred to as indexed sequential access method (ISAM)

sequential file organization

a style of file organization that means the records in a file are stored in sequential order of the primary key. When new records are to be added to a sequential file it is important to maintain the sequential order of all records (old and new combined)

sequence coding

a type of coding system where the records are numbered in order. This system is essentially the same as the counter primary key. Typically used to identify transactions.

19. In the hierarchy of data, a group of related ________ forms a field. a. bytes b. bits c. records d. data sets e. formats

a. bytes

8. In a _________ code, the code itself is suggestive of the item being coded. a. mnemonic b. group c. block d. sequence e. alphabetic

a. mnemonic

9. Which of the following statements is TRUE regarding batch vs. online input and file update? a. online updating requires online input b. online input must result in online updating c. batch input is faster than online input d. batch updating results in the master file being always up to date e. magnetic tapes can be used for online input and updating

a. online updating requires online input

16. A ________ file is accessed during a file maintenance run but not updated. a. reference b. backup c. history d. master e. a and d

a. reference

reference files

also called table files, a file type that are used to store relatively permanent information that is needed only for reference purposes during a maintenance run. These files can be updated periodically, but are accessed only for reference purposes during the process of updating a master file

random file organization

also referred to direct access files. Files are scattered throughout the storage medium (usually magnetic disk). Records are not stored in any physical order. A hashing routine is used to determine the storage location of records. The hashing routine takes the primary key of a record and applies some mathematical algorithm to generate a disk address for the record. To access the record, the hashing is applied to its primary key to determine its storage location. Duplicate disk addresses are referred to as clashes. Such clashes are stored in an overflow area on a magnetic disk

20. __________ represents raw facts, whereas ___________ is data made meaningful. a. Information, reporting b. Data, information c. Information, bits d. Records, bytes e. Bits, bytes

b. Data, information

5. If a file has two unique identifiers, each is called a __________ key. a. primary b. candidate c. composite d. foreign e. concatenated

b. candidate

6. When two or more fields together serve as the primary key in a file, the key is called a a. foreign key b. concatenated key c. secondary key d. candidate key e. none of the above

b. concatenated key

10. Which of the following steps is not necessary in an online file update system? a. editing b. sorting c. calculating d. file maintenance e. all of the above are necessary

b. sorting

13. A _______ field format allows only one of two possible values. a. text b. numeric c. boolean d. currency e. date/time

c. boolean

18. In the hierarchy of data, a group of _______ makes up a _______. a. bytes, bit b. fields, table c. fields, record d. tables, record e. files, record

c. fields, record

12. In the data processing cycle, deleting the record for customer ABC would occur during the a. information output stage b. data processing stage c. file maintenance stage d. data input stage e. data preparation stage

c. file maintenance stage

17. __________ files are relatively temporary while _______ files are relatively permanent. a. master, reference b. reference, master c. transaction, master d. history, transaction e. ledger, journal

c. transaction, master

7. A file may have more than one ___________________ but can have only one ____________. a. primary keys, secondary key b. primary keys, concatenated keys c. unique identifiers, primary key d. unique identifiers, secondary key e. primary keys, unique identifiers

c. unique identifiers, primary key

15. For information to have value, it must be a. relevant b. reliable c. unprocessed d. a and b e. a and c

d. a and b

14. A coding system in which ranges of numbers are reserved for each category of the item being coded is called a ___________ coding system. a. group b. sequence c. numeric d. block e. range

d. block

1. Buffers facilitate _________ of tightly connected sub-systems. a. controlling b. escalating c. integration d. decoupling e. management

d. decoupling

3. Every file must have one _______ and may have one or more __________ . a. non-key attribute, foreign keys b. foreign key, non-key attributes c. foreign key, primary keys d. primary key, non-key attributes e. concatenated key, primary keys

d. primary key, non-key attributes

understanding system

developing an understanding of what a system actually does is critical. The most logical way to do this is to divide a larger system into smaller parts. This process is known as factoring. The factored parts are known as subsystems and generally form hierarchical structures. The difficulty with factoring is that the number of interconnections between these subsystems, known as interfaces, increases rapidly. number of interconnections (i) number of subsystems (ns) I = [(ns)*(ns-1)]/2

11. _____________ fields can store any keyboard character. a. Currency b. Boolean c. Blobs d. Numeric e. Text (alphanumeric)

e. Text (alphanumeric)

4. Editing and sorting the data file are steps performed during the ________ stage in the data processing cycle a. data input b. data processing c. file maintenance d. information output e. data preparation

e. data preparation

2. Per the General Systems Model, every system must have each of the following except a. inputs b. process(es) c. outputs d. boundary e. repository

e. repository

general systems model

embraces the systems approach, the model defines a system as a set of elements that operate together to achieve some objective. A system has inputs, processes, outputs, a boundary, and operates in an environment Environment input ----> input ----> Process ---->output input ----> (the system) ^ Boundary (defines what is contained inside the system)

counter

field format that automatically increments lines by one whenever a new record in the file is created

boolean

field format that can have one of two possible values (true/false, yes/no)

numeric

field format that can only store numbers

date/time

field format that stores dates or times in a variety of user-specified formats. Can do date only, time only, or both date and time

currency

field format that stores dollar and cent amounts - all monetary values

nonkey attributes

fields or attributes in a file that are not part of the primary key are referred to as this

backup files

file types that are duplicate copies of transaction, master, and reference files. They should be maintained on site as well as off site at a secure location

black box

if the process inside a system in the general systems model is not understood, the system is termed this

systems approach

is a way of thinking about an information system and how its component interact with one another. The approach involves taking a holistic view such that the system is seen as more than just the sum of its parts. Problems, constraints, and potential solutions are examined from the entire system's point of view and not just at the subsystem or component level.

information

is data made meaningful. Alone, ____ is only a means to an end. Delivered at the right time and interpreted in the right manner can lead to knowledge.

candidate key

keys when there are multiple unique identifiers in a file that could be the primary key

secondary key

one or more of the nonkey attributes in a file can be designated as secondary keys. Are used to sort the file in some sequence for reporting purposes or to answer user queries. Making these is costly and while each nonkey attribute could be one, it is important to only mark important ones

data

represents raw, unprocessed facts that are useless without further processeing

bits

the lowest level of data. It is a binary digit that can take on the value of either 0 (turned off) or 1 (turned on). All computer systems store data in this form

concatenated key

the name of the primary key when a combination of fields are needed to uniquely identify records in a file

file maintenance run

the process of using transaction file information to update the appropriate master files

batch data input

the process where data is recorded on paper and subsequently entered into the computer system

True

true or False: Subsystems can be clustered. In this way, we can group closely related subsystems and assume that there is a single interface and ignore any weak connections. RAM is used as a buffer to allow the decoupling of computers from peripheral devices like printers which operate much slower than computers. The loosening of connections is called decoupling.

online data input

when data is entered instantaneously into the computer system, the process is called this.