CH.9 CIS 330

What is cardinality, and what symbols do you use in the crow's foot notation method

the number which suggests that the way one entitiy is linked tot he other symbols: single bar: one twofold bar: one and only one a circle: zero crow's foot: many

database management system (DBMS)

A collection of tools, features, and interfaces that enables users to add, update, manage, access, and analyze data in a database.

query by example (QBE)

A language allows the user to provide an example of the data requested.

logical record

A logical record contains field values that describe a single person, place, thing, or event. Application programs see a logical record as a set of fields, regardless of how or where the data is stored physicall

relational model

A model used in relational databases. The relational model was introduced during the 1970s and became popular because it was flexible and powerful.

international Organization for Standardization (iSO)

A network of national standards institutes from 140 countries working in partnership with international organizations, governments, industry, business, and consumer representatives. The ISO acts as a bridge between public and private sectors.

Y2K issue

A problem faced by many firms in the year 2000 because their computer systems used only two digits to represent the year; most dates now use a four-digit format for the year (YYYYMMDD).

normalization

A process by which analysts identify and correct inherent problems and complexities in their record designs.

SQL (Structured Query Language)

A query language that allows PC users to communicate with servers and mainframe computers.

repeating group

A set of one or more fields that can occur any number of times in a single record, with each occurrence having different values.

ODBC (open database connectivity)

An industry-standard protocol that makes it possible for software from different vendors to interact and exchange data.

data warehouse

An integrated collection of data that can support management analysis and decision making.

orphan

An unassociated or unrelated record or field. An orphan could be created if a customer order was entered in an order table where that customer did not already exist in the customer table. Referential integrity would prevent the creation of this orphan.

nonkey field

Any field that is not a primary key or a candidate key is called a nonkey field.

derivation code

Combining data from different item attributes, or characteristics, to build the code. Most magazine subscription codes are derivation codes.

file

Each file or table contains data about people, places, things, or events that interact with the information system.

table

Each file or table contains data about people, places, things, or events that interact with the information system.

functionally dependent

Functional dependence is an important concept for understanding the second normal form (2NF). The field X is said to be functionally dependent on the field Y if the value of X depends on the value of Y. For example, an order date is dependent on an order number; for a particular order number, there is only one value for the order date. In contrast, the product description is not dependent on the order number. For a particular order number, there might be several product descriptions, one for each item ordered.

economy of scale

The inherent efficiency of high-volume processing on larger computers. Database design allows better utilization of hardware. If a company maintains an enterprise-wide database, processing is less expensive using a powerful mainframe server instead of using several smaller computers.

cipher code

Use of a keyword to encode a number. A retail store, for example, may use a 10-letter word, such as CAMPGROUND, to code wholesale prices, where the letter C represents 1, A represents 2, and so on. Thus, the code, GRAND, would indicate that the store paid $562.90 for the item

key fields

Used during the systems design phase to organize, access, and maintain data structures. The four types of key fields are primary keys, candidate keys, foreign keys, and secondary keys

permissions

User-specific privileges that determine the type of access a user has to a database, file, or directory. Also called user rights

alphabetic code

Uses alphabet letters to distinguish one item from another based on a category, an abbreviation, or an easy-to-remember value, called a mnemonic code.

alphabetic code .

Uses alphabet letters to distinguish one item from another based on a category, an abbreviation, or an easy-to-remember value, called a mnemonic code.

What are data warehousing and data mining? How do businesses use these tools?

data warehousing is to store the data at a single location and data mining is the process of accessing the data based on particular patterns and relationships

data manipulation language

A data manipulation language controls database operations, including storing, retrieving, updating, and deleting data. Most commercial DBMSs, such as Oracle and IBM's DB2, use a DML.

relational database

A database in which tables are related by common fields, creating a unified data structure that provides improved data quality and access.

foreign key

A field in one table that must match a primary key value in another table in order to establish the relationship between the two tables.

secondary key

A field or combination of fields that can be used to access or retrieve records. Secondary key values are not unique. For example, to access records for only those customers in a specific postal code, the postal code field could be used as a secondary key.

primary key

A field or combination of fields that uniquely and minimally identifies a particular member of an entity. For example, in a customer table the customer number is a unique primary key because no two customers can have the same customer number. That key is also minimal because it contains no information beyond what is needed to identify the customer.

file-oriented system

A file-oriented system, also called a file processing system, stores and manages data in one or more separate files.

binary storage format

A format that offers efficient storage of numeric data. For example, when numeric data types are specified using Microsoft Access, there are a variety of storage formats choices, including integer and long integer, among others.

entity-relationship diagram (ERD)

A graphical model of the information system that depicts the relationships among system entities.

character

A group of eight bits is called a character, or a byte. A set of bytes forms a field, which is an individual fact about a person, place, thing, or event.

second normal form (2NF)

A record design is in second normal form (2NF) if it is in 1NF and if all fields that are not part of the primary key are dependent on the entire primary key. If any field in a 1NF record depends on only one of the fields in a combination primary key, then the record is not in 2NF. A 1NF record with a primary key that is a single field is automatically in 2NF.

first normal form (1NF)

A record is said to be in first normal form (1NF) if it does not contain a repeating group (a set of data items that can occur any number of times in a single record).

unnormalized

A record that contains a repeating group, which means that a single record has multiple occurrences of a particular field, with each occurrence having different values.

Unicode

A relatively recent coding method that represents characters as integers. Unlike EBCDIC and ASCII, which use eight bits for each character, Unicode requires 16 bits per character, which allows it to represent more than 65,000 unique characters.

standard notation format

A representation that makes designing tables easier as it clearly shows a table's structure, fields, and primary key.

code

A set of letters or numbers that represents a data item. Codes can be used to simplify output, input, and data formats.

data mart

A specialized database designed to serve the needs of a specific department, such as sales, marketing, or finance. Each data mart includes only the data that users in that department require to perform their jobs.

JDBC (Java database connectivity)

A standard that enables Java applications to exchange data with any database that uses SQL statements and is ODBC-compliant.

tuple

A tuple (rhymes with couple), or record, is a set of related fields that describes one instance, or member of an entity, such as one customer, one order, or one product. A tuple might have one or dozens of fields, depending on what information is needed.

market basket analysis

A type of analysis that can detect patterns and trends in large amounts of data.

crow's foot notation

A type of cardinality notation. It is called crow's foot notation because of the shapes, which include circles, bars, and symbols, that indicate various possibilities. A single bar indicates one, a double bar indicates one and only one, a circle indicates zero, and a crow's foot indicates many.

combination key

A type of data validation check that is performed on two or more fields to ensure that they are consistent or reasonable when considered together. Even though all the fields involved in a combination check might pass their individual validation checks, the combination of the field values might be inconsistent or unreasonable

M:N

A type of entity relationship. A many-to-many relationship, abbreviated M:N, exists when one instance of the first entity can be related to many instances of the second entity, and one instance of the second entity can be related to many instances of the first entity.

1:M

A type of entity relationship. A one-to-many relationship, abbreviated 1:M, exists when one occurrence of the first entity can be related to many occurrences of the second entity, but each occurrence of the second entity can be associated with only one occurrence of the first entity.

1:1

A type of entity relationship. A one-to-one relationship, abbreviated 1:1, exists when exactly one of the second entity occurs for each instance of the first entity.

referential integrity

A type of validity check. Referential integrity is a set of rules that avoids data inconsistency and quality problems.

subschema

A view of the database used by one or more systems or users. A subschema defines only those portions of the database that a particular system or user needs or is allowed to access.

query language

Allows a user to specify a task without specifying how the task will be accomplished. Some query languages use natural language commands that resemble ordinary English sentences

abbreviation code

Alphabetic abbreviation. For example, standard state codes include NY for New York, ME for Maine, and MN for Minnesota.

common field An attribute that appears in more than one entity. Common fields can be used to link entities in various types of relationships

An attribute that appears in more than one entity. Common fields can be used to link entities in various types of relationships.

associative entity

An entity that has its own set of attributes and characteristics. Associative entities are used to link between many-to-many (M:N) relationships.

significant digit code

Cipher that distinguishes items by using a series of subgroups of digits. U.S. Postal Service zip codes, for example, are significant digit codes.

category code

Cipher that identifies a group of related items. For example, a local department store may use a two-character category code to identify the department in which a product is sold.

block sequence code

Cipher that uses blocks of numbers for different classifications.

mnemonic code

Ciphers using a specific combination of letters that are easy to remember. Many three- character airport codes are mnemonic codes. For example, LAX represents Los Angeles.

cardinality notation

Code that shows relationships between entities.

What is a DBMS? Briefly describe the components of a DBMS

DBMS called database management system can defined as a set of tools that facilitate to perform operations like adding, updating, accessing, managing, sorting, filtering and also analysing with the mode of interface system and features included in it.

What are entity-relationship diagrams and how are they used? What symbol is used for a relationship? What is an associative entity?

Entity-relationship diagrams (ERDs) are graphical representations of an informationsystem. They are used to show how each entity relates to the other entities in the system, but they do not show the flow of data through the information system. A rectangle is used torepresent an entity, while relationships are represented by diamonds. Cardinality describeshow an entity relates to other entities in the ERD. In a specific relationship, an entity canbe mandator y, meaning it must be present, or optional, meaning it may be present. Crow's foot notation displays cardinality in a graphical manner using symbols. A single bar indicates one possibility, a double bar means one and only one, a circle indicates zero and a crow's foot indicates many possibilities

action code

Indicates what action is to be taken with an associated item. For example, a student records program might prompt a user to enter or click an action code such as D (to display the student's record), A (to add a record), and X (to exit the program)

physical storage

Information storage mechanism that is strictly hardware-related, because it involves the process of reading and writing binary data to physical media, such as a hard drive, flash drive, or DVD.

data mining

Looking for meaningful patterns and relationships among data. For example, data mining software could help a consumer products firm identify potential customers based on their prior purchases.

sequence code

Numbers or letters assigned in a specific order. Sequence codes contain no additional information other than an indication of order of entry into a system.

Describe a primary key, candidate key, secondary key, foreign key

Primary key-An attribute that uniquely identifies each row in a relation Candidate key- An attribute that is unique that has the potential to become a Primary Key foreign key - An attribute that is also a Primary Key of another entity that links two tables together. secondary key- One field or a combination of fields for which more than one record may have the same combination values.

recovery procedure

Process for restoring data and restarting a system after an interruption. Recovery procedures can be used to restore a file or database to its current state at the time of the last backup.

audit log files

Record details of all accesses and changes to a file or database and can be used to recover changes made since the last backup.

clickstream storage

Recording web visitor behavior and traffic trends for later data mining use.

logical storage

Refers to information as seen through a user's eyes, regardless of how or where that information is organized or stored.

database administrator

Someone who manages a database management system (DBMS). The DBA assesses overall requirements and maintains the database for the benefit of the entire organization rather than a single department or user.

multivalued key

Sometimes it is necessary for a primary key to consist of a combination of fields. In that case, the primary key is called a combination key, composite key, concatenated key, or multivalued key.

composite key

Sometimes it is necessary for a primary key to consist of a combination of fields. In that case, the primary key is called a combination key, composite key, concatenated key, or multi- valued key.

candidate key

Sometimes it is possible to have a choice of fields or field combinations to use as the primary key. Any field that could serve as a primary key is called a candidate key.

audit fields

Special fields within data records to provide additional control or security information. Typical audit fields include the date the record was created or modified, the name of the user who performed the action, and the number of times the record has been accessed.

table design

Specifies the fields and identifies the primary key in a particular table or file. third normal form (3NF) A record design is in third normal form (3NF) if it is in 2NF and if no nonkey field is dependent on another nonkey field. A nonkey field is a field that is not a candidate key for the primary key.

ASCii

Stands for American Standard Code for Information Interchange, a data storage coding method used on most personal computers and workstations

ASCii

Stands for American Standard Code for Information Interchange, a data storage coding method used on most personal computers and workstations.

EBCDiC

Stands for Extended Binary Coded Decimal Interchange Code, a coding method used on mainframe computers and some high-capacity servers.

clicks to close .

The average number of page views to accomplish a purchase or obtain desired information.

schema

The complete definition of a database, including descriptions of all fields, records, and relationships.

backup

The process of saving a series of file or data copies to be retained for a specified period of time. Data can be backed up continuously, or at prescribed intervals

bit

The smallest unit of data is one binary digit.

absolute date

The total number of days from some specific base date. To calculate the number of days between two absolute dates, subtract one date from the other. For example, using a base date of January 1, 1900, September 27, 2012, has an absolute date value of 41179 and July 13, 2011, has an absolute date of 40737. If the earlier date value is subtracted from the later one, the result is 442 days.

What is an unnormalized design, and how do you convert an unnormalized design to 1NF?

To convert a unnormalised data design in into 1NF or into first normal form, all the groups must be removed. Each row and column should have only atomic values

byte

byte called a byte, or a character. A set of bytes forms a field, which is an individual fact about a person, place, thing, or event.