Chapter 11: Behind the Scenes: Databases and Information Systems
Life Without Databases
▯ Database is a collection of related data that can be easily stored, sorted,
organized, and queried
▯ A key attribute of databases is that information can be filtered so that you
can only see the info you really want (ex. Facebook)
Should I use databases for managing all types of data?
▯ NO, simple lists can be created on word processing or spreadsheet software,
a spreadsheet in Microsoft excel, or table in Word
When is a list not appropriate?
▯ If complex information needs to be organized or more than one needs access
to it, a list is not an efficient solution
▯ A great deal of duplicated data between the two lists
▯ Data redundancy is when the same data exists in more than one place in a
▯ Each time the information in the list changes, multiple lists must be updated
Aside from data redundancy and inconsistency, are there any other problems
with using lists instead of databases?
▯ With a list, anything can be entered in a row or column, even if that
information is incorrect
▯ Information can be organized in many ways
▯ How to handle incomplete data
Cant I Just exercise caution and set rules for updating lists?
▯ Being careful does not avoid the most pressing problems or lists:
1. Inability of data to be shared
2. Data redundancy
How can I solve the problems associated with lists?
▯ Single topics: lists is sufficient
▯ Complex data: a database is sufficient
Database Building Blocks
Advantages to Databases
How do databases make out lives easier?
▯ Allow easy retrieval and storage of large quantities of info
▯ Extremely large electronic databases can provide info in seconds
▯ THREE main ADVANTAGES:
1. Enable info storing
2. Promote data integrity
3. Flexible use of data
How do databases make information sharing possible?
▯ One file is maintained, which reduces errors and increases efficiency 2
How do databases promote data integrity?
▯ Data integrity means that the data contained in the database is accurate and
▯ Data centralization is having all your data in one central location. It helps
ensure data integrity by requiring data to be updated only by one place if the
How do databases provide flexibility?
▯ You can reorganize the info they contain in a variety of ways to suit the needs
of the moment
▯ Data flexibility makes info dissemination tasks easier
Disadvantages with databases
▯ More complex to construct
▯ Time-consuming, and expensive
▯ Great care must be involved to ensure they will function properly
▯ Database administrator (or database designer) is an individual trained in
the design and building of databases, to assist with the construction of large
▯ Data privacy
How is data stored in a database?
▯ THREE main COMPONENTS: fields, records, and tables
What is a field?
▯ Displayed in columns
▯ Each field is identified by a field name which is way of describing the field
What are data types?
▯ A data type is assigned when fields are created in a database
1. Text field holds words
2. Numeric field holds numbers
3. Computational field (computed field) numeric field that stores
4. Data field holds data such as bdays and due dates
5. Memo field holds long pieces of text
6. Object field holds pictures, video clips, or documents
7. Hyperlink field stores hyperlinks to webpages
What is meant by a field size?
▯ Is the max number of characters or numbers that a field can hold
▯ If numeric field has a size of 5 it can hold a number as large as 99999
What are records and tables?
▯ A record is a group of related fields
▯ A table is a group of related records
Can fields have the same values in the same table? 3
▯ YES, two students may have the same last name
▯ A primary field or key field is one field that has a value unique to that
What makes a good primary key?
1) Relational Databases
What is a relational database?
▯ Organizes data in table format by logically grouping similar data in relation
▯ Tables are logically linked to each other by including their primary keys in
other tables with related info
Who invented the relational database?
▯ E. F. Codd in 1970
2) Object-Oriented Databases
What is an object-oriented database?
▯ Stores data in objects rather than in tables
▯ Objects contain not only data, but also methods for processing or
manipulating that data
▯ These databases store more types of data and able access to data faster
Why would I use an object-oriented database?
▯ They are more adept at handling unstructured data. Ex, audio clips, video
clips, pictures, and extremely large documents
▯ Binary Large Object (BLOB) is known as this data because it is actually
encoded in binary form
▯ Are more complex
▯ Need a query language to access and manage data, object query language
(OQL) is similar to structured query language
3) Multidimensional Databases
What is a multidimensional database?
▯ Stores data in more than two dimensions
▯ Organize data in cube format
▯ Each data cube has a measure attribute which is the main type of data that
the cube is tracking
▯ Feature attributes describe the measure attribute in some meaningful way
What are the advantages of multidimensional databases?
▯ Can be easily customized to provide information to a variety of users
▯ Can process data much faster than pure relational databases can 4
▯ Example, Oracle Corporation
Database Management Systems: Basic Operations
▯ Database management system (DBMS) interacts with the user, other
applications, and the database to capture and analyze data
▯ FOUR main OPERATIONS:
1. Creating databases and entering data
2. Viewing and sorting data
3. Querying (extracting) data
4. Outputting data
Creating Databases and Entering Data
How do I create a database with DBMS?
▯ Define the data to be captured
▯ Create description of the data (data dictionary or data schema)
▯ Data dictionary defines the name, data type, and length of each field in the
How do I know what fields are needed in my database?
▯ Each field should describe a unique piece of data and should never combine
two separate pieces of data
What does a data dictionary look like, and how do I create one?
▯ In Microsoft Access data dictionary is called Field Properties Box
▯ To create one there are 4 steps:
1. Create a field name (field names should be unique within a table
2. Define a data type for each field
3. Set a max field size for the field
4. Set a default value which is the value the database uses for the field unless
the user enters another value
▯ Repeat these steps for each field in the table
▯ Metadata is data that describes other data
What happens if I forget to define a field in the data dictionary or if I want to
add another one later?
▯ You can add additional fields as needed but this does not negate the need for
proper planning and design of a database
How do I get data into a database?
▯ After creating a data dictionary for each table in the database and establish
the fields you want the database to contain
▯ Create individual records, and input data by keying it into the database
▯ A better way is to import data electronically from other application files
▯ Databases use filtering to determine if the data is the correct format
How can I make manual entry into a database more convenient?
▯ Create an input form which provides a view of the data fields to be filled,
with appropriate labels to assist database users in populating the database 5
How can I ensure that only valid data is entered into the database?
▯ Validation is the process of ensuring that data entered into the database is
correct and complete
▯ Validation Rule is a rule that is set up in a database to alert the user to the
possible wrong entries
How does a range check work?
▯ Range check ensures that the data entered into the database falls within a
certain range of numbers
▯ Field constraint is any property that must be satisfied for an entry to be
accepted into the database field
What does a completeness check accomplish?
What is the function of a consistency check?
▯ Compares the values of data in two or more fields to see if these values are
How are alphabetic and numeric checks used?
▯ Alphabetic check confirms that only textual characters are entered in a field
▯ Numeric check confirms that only numbers are entered in the field
Viewing and Sorting Data
How can I view the data in a database?
▯ Displaying the data on-screen and browsing through the data
How can I reorder records in a database?
▯ Sort a database into order you need
What if I want to find a particular piece of data in a database?
▯ Browsing records: for small databases
▯ Request the data you are seeking: for large databases
Extracting or Querying Data
What is a query?
▯ A query is a question or inquiry
▯ A database query is a question you ask the database so that it provides you
with the records you wish to view
Is querying a database as simple as just asking the proper question?
▯ A software uses a query language which retrieves and displays records
▯ Structured Query Language (SQL)
Do I have to learn a query language to develop queries for my database?
▯ There are Wizards
How do I get data out of a database?
▯ Viewable electronic report (summary report)
Can I transfer data from a database to another software application? 6
▯ Exporting data involves putting it into an electronic file in a format that
another application can understand
Relational Database Operations
▯ The link between tables that defines h