Download ICT Database Lesson 1

ICT Database
Lesson 1
What is a Database
Objectives
•9.1.1: Describe the functions of a relational database.
•9.1.2: Distinguish between databases and spreadsheets.
•9.1.3: Identify advantages of using a database instead of
alternatives (e.g., spreadsheets, electronic documents,
paper).
•9.1.4: Describe real-world uses for databases, including
search engines, schools, hospitals, retail.
Database
A file that stores data in an organized fashion so that
information can be retrieved from it.
Examples:
• iPod playlist
• Netflix movie list
• Contacts in cell phone
Table – Flatfile Database
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A collection of data organized in rows and columns that
can be used to store and manage information
Work great with small lists of data (information) that is all
related.
A simple way to create a flat file database is to use a
spreadsheet.
Store information in cells created by using columns and
rows of data
Spreadsheets - Advantages
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Great for analyzing and sorting related data.
Easy to learn and use
Suitable for storing and "crunching" relatively small
volumes of numerical data.
Able to present numerical data in the graphical form to
quickly analyze data.
Spreadsheets - Disadvantages
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Require that you enter the same information in multiple
places
Have simplistic sorting and querying capabilities
Contain only a finite number of records
Changes to data in the computer memory and are not
complete until the file is saved
Data Integrity
The validity of the data
“Garbage in, garbage out.”
Arizona / ARIZONA / Ariz / ARIZ / Az / AZ.
Creating Tables
1. Identify duplicate data
2. If duplicate data exists, create a separate table just for that
data
3. Relate it back to the original table
Relational Database
Consists of multiple tables of information related through
common fields
Advantages
1. They can hold an unlimited number of records up to 1 gigabyte
of storage.
2. A database allows for the simultaneous access and query of
data by multiple individuals in multiple locations.
3. Data is protected against inadvertent corruption so you no
longer need to keep redundant data.
4. We don’t have to manually enter the information reducing time,
effort and mistakes.
5. Entering information is minimalized which reduces input time,
resources and opportunities for human error. This reduces
cost and increases data integrity.
6. Reduced processing time for large amounts of data.
Disadvantages
1. They are more complex and harder to learn and use than
spreadsheets
2. Designing relational tables can be more difficult and timeconsuming
3. and software and hardware costs are higher than a
spreadsheet.
Big Data
A term that describes enormous volumes of data that are too
huge for regular database programs
• Unlike data in a database, big data is unstructured and
unrelated.
• Analysis of big data requires specialized tools.
ICT Database
Lesson 2
Designing a Database
Objectives
• 9.2.1: Identify the components of a database.
• 9.2.2: Distinguish between fields and records in a database.
• 9.2.3: Describe the basic data types and formats used in a database.
• 9.2.4: Distinguish between a table and a query.
• 9.2.5: Identify database keys, including primary and foreign.
• 9.2.6: Identify the relationships between tables in a database (i.e., oneto-one, one-to-many, many-to-many).
• 9.2.7: Distinguish between a query and a report.
• 9.2.8: Identify various report types.
Steps to Designing a Database
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Who needs what information
Organize data tables and fields
Relate the information
Identify data types
Identify Queries, Forms and Reports
Fields
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Specific categories of information we need to track per
type of information
Variables organized as columns in a table
Record
A group of fields in a table related to a single entity and is
contained in a row within that table
Primary & Foreign Key
Primary Key: uniquely identify each record in a table and help
to link related records
• Data contained in the primary key is unique — that is, no
duplicate data can be contained in the field.
Foreign Key: a field that refers back to a primary key in
another table
• Will reference a unique column in another table
• This primary key – foreign key relationship is how you link
the tables.
Primary & Foreign Key
Primary & Foreign Key
Primary
Key
Primary Key relates to the
Foreign Key of the second table
Foreign
Key
Table Relationships
Database Table
Relationship
Description
One-to-one
Each record in Table A can have only one matching record in
Table B, and vice versa.
The relationship is created only if both of the related fields are
primary keys.
One-to-many
A record in Table A can have multiple matching records in Table
B, but a record in Table B has only one matching record in Table
A.
The relationship is created only if the related field is the primary
key in Table A and a foreign key in Table B.
Many-to-many
One record in Table A can relate to many matching records in
Table B, and vice versa.
Table Relationships
One-to-many
relationship
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Many-to-many
relationship
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Junction (Join)Tables
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A 3rd unique table created to join two unrelated tables
Contains the primary key fields from each of the other two
tables in the relationship
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Junction
Table
Primary
Fields
Primary
Fields
Data Types
• Text – Alphanumeric values, examples are names, and titles. This field can hold between 1255 characters.
• Integer – Numeric values, such as calculations and distance. This does not include currency.
There is no decimal and precision is 10 places.
• Float – Numeric values that have 2 decimal points and precision up to 16 places.
• Currency – Numeric values that describe money.
• Date/Time – Dates and Time.
• Yes/No – Boolean values, use when the only options are true or false.
• Memo – Long formatted text fields more than 255 characters. A memo is the right choice for
a description of an item.
• Attachment – Digital media such as pictures. A record can have more than one attachment.
• Hyperlink – Links to other resources such as Web sites, and e-mail addresses.
• Autonumber – Provides a unique numeric value that only appears once in a table. If you
delete an autonumber, that number will never appear again in that table. Many databases
use an Autonumber as the primary key in record.
Form
Provides a simplified interface for entering, modifying, and
viewing the database records
SQL – Structured Query Language
A sub-language commonly used for developing and
managing databases
•SQL pronounced “sequel”
•Used primarily in a database to retrieve, update, insert
or remove information
•Sufficiently powerful and can create tables,
restructure tables and remove tables, among other
very complex tasks
Database Management Systems
A program used to store, access and manipulate database
information
• Microsoft Access is an end-user DBMS that you can use to
create and manipulate fairly small and uncomplicated
databases
• Oracle, MySQL, IBM’s DB2 and Microsoft SQL Server are
high-end DBMS programs used to create and manipulate
large, complex databases used in large organizations
ODBC - Open Database Connectivity
•An open standard application programming interface (API)
•Allows us to use the MS Access interface tools to access the
DBMS data.
Using a simplified graphical user interface (GUI) like MS
Access to build queries and reports is a flexible way for a
relative novice to gain access to a wealth of company data.
ICT Database: Lesson 3
Creating and Managing
Tables
Inserting Records
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Adding information to a set of database fields
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Manually enter in Datasheet View or Form – small
amounts of data
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Import data for a large number of records
Usually a spreadsheet, another database, or as a text file (.txt,
.csv)
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Map corresponding fields
Updating Records
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Updating or modifying information in an existing set of
fields
Datasheet View for limited amounts of data
SQL routine for larger sets of data
Deleting Records
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Information is permanently deleted from the database
Datasheet View for small amounts of data
SQL routine for larger amounts of data
Must make sure to delete all related material in related
tables
May impact other database objects
Database Schema
The skeleton structure that represents the logical view of the
entire database.
Lists:
• The tables to be used in the database
• each of the fields to be included in each of the tables
• the data type of each of the fields
• and the relationship among the various tables.
It also includes all the constraints that are to be applied on
the data.
Database Schema
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Datasheet View
• Displays fields in a table similar to how it would look in a spreadsheet
• Rows and columns
• Columns are fields
• Rows are records
• Can add or edit fields
• Can add, modify or delete records
Design View
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Displays and edit table and field properties
 Data type
 Default value
 Required
ICT Database: Lesson 4
Manipulating and Sharing Data
Common Errors
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Mistyping data or entering the wrong data type
 Data integrity can be improved using field properties:
format, length, or a “mask” (date/time or (xxx) xxxxxxx)
Referring to a non-existent table or field.
 The name of the table may have been changed or the
table may have been deleted.
Syntax errors – rules for wording or commands
Checking the status of a table should be the first step in
troubleshooting
Query
A question that you ask a database using a set of
criteria and in return the database provides its answer
Will display only the particular fields and records from a
database you want to see
Data returned by a query can come from tables, other
queries or reports
Automatically create a join between Primary and Foreign Key
Query Example
List all pool companies that have
purchased BN-0609-TGOLD bullnose and
what is my price?
Types of Queries: Select
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The simplest type of query and most common
Used to select and display data from either a single table
or a group of tables depending on what information is
wanted
It creates a "virtual" table where the data is displayed and
kept. The data in a virtual table can only be changed 1
record at a time
Types of Queries: Action
• Creates a specific action to be performed on the database
• Examples: creating new tables, deleting rows from existing ones and
updating records or creating entirely new ones.
• Popular query to run because they allow for many records to be changed
at one time
• Five kinds of action queries are:
1. Insert Query – adds data to an existing table
2. Append Query – takes the set results of a query and "appends"
(or adds) them to an existing table
3. Delete Query – deletes records from the table based on the
results of the query
4. Make Table Query (Create) – creates a table based on the results
of a query
5. Update Query – allows for one or more fields in a table to be
updated
Importing / Exporting Data
•Exporting data prepares the data to be used in other
programs such as spreadsheet programs.
•Importing prepares data to be used in the open program
 Import data for a large number of records.
 Usually a spreadsheet, another database, or as a text file
(.txt, .csv)
 Map corresponding fields
Reports
A way to display your data in a visually appealing and
easy-to-read format.
You can format the data for different types of reports
• group and/or sort data, display subtotals, averages
and other statistical data
• highlight values by using conditional formatting
• apply themes to enhance the "look and feel" of
reports
• add images to reports
• preview and print reports
Reports
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Reflect current data only at the time the report is run
Reports tool provides the fastest way for you to create a
report
 Generates a report immediately without prompting
you for information
 Displays all the fields from the underlying table or
query
Reports: Controls - Themes
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Controls: display data, perform actions, and let you view
and work with information that enhances the user
interface, such as labels and images.
Three types of controls: bound, unbound, and calculated
Allow you to manipulate data such as sorting or summing
a column
Themes alter the “look and feel” of database reports