DATA MANAGEMENT Flashcards
How is data organized?
i. Character: It is a
single letter, number, or special character, such as a punctuation mark, or a symbol.
ii. Field: group of related characters. A
data field represents an attribute of some
entity For example, a first name
iii. Record: A record is a collection of related fields. A record represents a
collection of attributes that describe an entity.
iv. Table: A table is a collection of related records. For example, the Payroll Table would include payroll information (records) for the employees
v. Database: A database is an integrated collection of logically related
tables. For example, the Personnel Database would include all related
employee tables including the Payroll Table and the Benefits Table.
What is a database?
: A structured collection of related data about one or more subjects.
What is the need for databases?
• Sharing: In organizations, information from one department can be
readily shared with others. E.g. Billing could let marketing know which customers ordered large quantities of merchandise.
• Security: Users are given passwords or access only to the kind of information they need. Thus, the payroll department may have
access to employees’ pay rates, but other departments would not.
• Less data redundancy: Without a common database, individual departments have to create and maintain their own data resulting
to data redundancy. Redundant data causes inefficient use of storage space and data maintenance problems.
• Data integrity: When there are multiple sources of data, each
source may have variations. A customer’s address may be listed as
“Main Street” in one system and “Main St.” in another. With
discrepancies like these, it is probable that the customer would be treated as two separate people.
What is DBMS?
Examples?
• In order to create, modify, and gain access
to a database, special software is required.
• This software is called a database management system(DBMS)
EG
Microsoft Access,
Oracle DB, MYSQL, Microsoft SQL Server
Why use DBMS?
• Data independence and efficient use of data, • for uniform data administration, • for data integrity and security, • concurrent access to data, and • data recovery from crashes among others
What are the five principal database models
hierarchical, network, relational, and
object-oriented
Describe Hierachical Database
Hierarchical
database uses nodes to link and structure
fields and records; entries may have one
parent node with several child nodes in a one-to-many relationship
*See phone for pic
Describe Network Database:
Network database is
like hierarchical except a child node may
have more than one parent in a many-to many relationship; additional connections
are called pointers.
Describe Relational Database
Relational database
data is stored in tables (relations); related
tables must have a common data item (key field). A table and its data are called a
relation.
Describe Object-Oriented Database:
Object oriented databases store data,
instructions, and unstructured data.
Data is organized using classes(general definitions), objects(specific instances of a class that can contain both data and instructions to manipulate the data),
attributes( data fields an object possesses), and methods(instructions for
retrieving or manipulating attribute
values).
.
What are the skills required to use a database?
• Add new information and delete existing
information
• Search for information in the database
• Question the database
• Sort information alphabetically or numerically
• Run reports to produce simple or elaborate
printouts
Where are DBMSs used?
- Hospitals : Appointments, specializations,
- Airlines : reservations, schedules, etc.
- Entertainment : Recommendation, packages, costs
- Telecom : calls made, customer details, network usage, etc.
- Universities : registration, results, grades, etc
What are some job roles associated with database creation?
• Database Specialist: design and create
professional databases.
• Database Users: Access the database that have been created by the specialists. They
carry out data entry, data maintenance and
information retrieval.
• Database Administrators: provide access to specific data for database users. They are also responsible for recovery of databases after a crash or major errors
What should you consider before planning a database?
• What is the purpose of the database? • What detail do you want from it for information on screen or on printouts? • What information are you going to put into it? • How are you going to capture this information?
What is an index?
- An index allows a database to work faster when finding and sorting records.
- They work in a similar way to the way you would use an index in a traditional book
What are the examples of data types?
• Text: Stores alphanumeric text • Date/Time: Date and time • Yes/No: Boolean Values (True or false) • Number: Numeric values • OLE Object: Stores Images , documents, graphs • Currency: Monetary Data • Attachment: Any supported type of file • Hyperlink: Web address
What is a primary key?
•The field by which each record will be uniquely identified and by which relationships between tables can
be created.
• A table usually has only one primary key.
What are the advantages of a primary key
• Duplicate records are not allowed
• Primary key is often used to establish
relationships
• Index is automatically created for a primary key. This speeds up data retrieval and sorting
What is a foreign key?
• A foreign key points to a primary key in
another table.
• It shows relations between tables.
Give examples of Other Database Objects
• Queries: Allows the user to define exactly
what information from these tables they wish
to know. Queries are the main questioning
system in Microsoft Access- allowing users to extract and analyze data.
• Forms: Forms can be created to display
information contained in queries in a format
that is easy to work with.
• Reports: A report is an effective way to
present data from a table or query in a
printed format.
What are the Relationship Types for
linked tables
1.One-To-One- each record in the first table can have only one matching record in the second table, and each record in the second table can have only one matching record in the first table.
2.One-To-Many -This is the most common type of relationship. Here, a record in the first table can have many matching records in the second table, but a record in the second table has only one matching record in the first table.
3.Many-To-Many -A record in the first table can have many matching records in
the second table, and a record in the second table can have many matching records in the first table.
• Choose an application area /domain with which you are familiar.
• Identify at least five tables in for the database
• Create at least four field for each table with their corresponding data types
• Identify the primary keys and foreign keys for the tables.
• Create 2-3 relationships between the tables. Elaborate the types of relationships between
the tables.
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