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Introduction to Database SystemsIntroduction to Database Systems

• Introduction to Database Concepts• Introduce Microsoft Access• Tables, Queries, Forms, Reports

etc• Creating a simple database table• Indexing

Objectives:

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Data, Information, & DatabaseData, Information, & Database Data : A collection of numbers and text :

273448926 Information : Meaning derived from data

SSN # 273-44-8926 Database: A collection of related data stored in a

specific format to simplify retrieval. The phone book and dictionary are examples of databases.

John Smith’s SSN # 273-44-8926 DBMS – Database Management Systems are

programs that help in the storage and retrieval of information from databases. (Access, Oracle)

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DBMS Vs. Spreadsheets DBMS Vs. Spreadsheets Store and retrieve

data Provide support for

data “organizing” and selecting

Can do simple calculations

Efficient data handling

Customers of VISA with balance > 1000

Store and analyze data

Provide support for complex calculations

Can do simple data organizing and selecting

Inefficient data handling

What was the net profit of VISA

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Access DBMS

Objects

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Tables - a list of data organized into fields and records

Queries - question structures to sort, filter and select specific information

Forms - structures for screen views of data Reports - structures for written output of data Program Modules - program code to perform

specific actions

Access DBMS “objects”:

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A Database Management System

Data Tables

Reports

RelationshipsData Input:Onto TablesOnto FormsFrom files

OutputFiles

QueryResultsDBMS

Queries

Program Modules

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An Inventory Database SystemAn Inventory Database System

Tables:

Reports & Queries

Forms:

Order Transactions

New Vendors & New Customers

NewProducts

Shipments

Program Modules

Program Modules

CurrentInventory

CustomerAccounts

VendorList

OrdersOrderDetails

CustomerInvoices

Daily ShipList

AccountsPayable

InventoryLow Message

Output File:

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Data is stored in objects called Tables• Data on tables are listed in rows called records • A record consists of one or more ordered categories

called fields• Field types include Text. Number, Currency,

Date etc. Certain fields are required fields and must be filled

• Field Properties – format, validation rule, required, size, masks, defaults, ranges

A table is a listing of multiple records, all records in a table have the same fields

“Objects”: Tables

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Primary KeyPrimary Key

A field, or combination of fields, which uniquely identifies a record in a database

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Table Datasheet View: Bank CustomersTable Datasheet View: Bank Customers

Field RecordPrimaryKey

Customers: Tableacct# ssn lname fname address city state zipcode

456 123456789 Sommer Martín 5400 E. Broad ST Reynoldsburg OH 43213543 139555002 Suyama Michael 4110 Old Redmond Rd. Worthington OH 43201544 157745969 Lebihan Laurence 342 S. Drexel Bexley OH 43209999 123456789 Sommer Martín 5400 E. Broad ST Reynoldsburg OH 43213

1112 178301771 Berglund Christina 707 Oxford Rd. Columbus OH 432222456 201529842 Trujillo Ana 7 Houndstooth Rd. Marysville OH 420013064 227776183 Moos Hanna 29 King's Way Groveport OH 432873575 257436001 Citeaux Frédérique 3400 - 8th Avenue Suite 210 Columbus OH 432104456 290951508 Callahan Laura Coventry House Miner Rd. Dublin OH 432555323 328824082 Moreno Antonio 49 Gilbert St. Cleveland OH 40032

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A Second Table - “Transactions” keeps track of all deposits and withdrawals

A Second Table - “Transactions” keeps track of all deposits and withdrawals

• What’s the Primary key on this table?Account# date transaction$

456 4/1/2012 $1,231.39544 4/1/2012 $3,366.82

2456 4/2/2012 $2,301.683064 4/2/2012 $5,087.664456 4/3/2012 $12,838.425323 4/3/2012 $167.805566 4/4/2012 $641.92456 4/9/2012 ($1,186.26)544 4/9/2012 ($3,243.43)

1112 4/11/2012 $159.664456 4/12/2012 ($12,367.91)

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Walkthrough: Setting up a Table using Design View

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Divide Tables into Inseparable Fields

Address as 1 field – 17 Main St. New York, New York 10002

Address as 4 fields Street Address - 17 Main St. City - New York State - New York Zip code – 10002

If you wanted to filter the table to get a list of only New York City residents how would this work with these two different Table structures

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Defining Properties for each Field in a TableDefining Properties for each Field in a Table

For a person’s social security number use: What field type?

Text, Number - Short Integer, Number- Long Integer etc.

Should it be optional or required? Does the value need to be within certain

limits or from a predefined list? Is there a default value? Would an input mask be appropriate

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Memory and Field SizeMemory and Field Size

Text: Up to 255 characters

Memo: Up to 65,535 characters

Numbers: Integer - 2 bytes - 16 bits Long Integer - 4 bytes - 32 bits (*) Byte (character) - 1 byte Single - 4 bytes - -precision 7 Double - 8 bytes - -precision 15

Why adjust the field size for Social security number?

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How should you decide what information goes on which table?

How should you decide what information goes on which table?

If a fact appears in more than one record of a table, then this fact should probably be defined in another table. Example: Account number

Each fact change should change in only one place Example: Address

Calculations shouldn’t be part of the database Example: Current Balance

Select a Primary Key where applicable so you can relate your tables Example: Account number

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Tools: Sorting and Filtering Tools: Sorting and Filtering

Sorting - allows the user to temporarily order the records by a specific field Ascending or Descending order Single or multiple sort fields

Filtering - allows the user to view only specific records that meet the criteria Filter by form or filter by selection Specify a single criteria or use Boolean and/or

for multiple criteria in multiple fields

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Storing and Retrieving Records from TablesStoring and Retrieving Records from Tables

How are DBMS systems designed to efficiently handle data?

Data is stored on magnetic or optical disk in a linear fashion

To retrieve a specific record one would have to search them one at a time until the desired record is found.

To make data retrieval more efficient one can “index” a table based on a specific field.

Search routines could then be used on that field to more efficiently find the record

Example: Alphabetically sorting a dictionary and then analyzing the first letter of the criteria in the sorted list.

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Linear Search on Un-indexed FieldLinear Search on Un-indexed Field

Find the name of student for ss#606147775

• Go to the first record to see if 178301771 matches 606147775. If no match then check the next record until a match is found.

• Here it must check 11 items before you find the correct one. On average it will have to check #entries/2

ssn lname fname606147775 Anders Maria178301771 Berglund Christina988544806 Buchanan Steven290951508 Callahan Laura257436001 Citeaux Frédérique874775203 Davolio Nancy419975418 Dodsworth Anne371616449 Fuller Andrew536370683 Hardy Thomas774094122 King Robert157745969 Lebihan Laurence474621100 Leverling Janet227776183 Moos Hanna328824082 Moreno Antonio684995818 Peacock Margaret123456789 Sommer Martín139555002 Suyama Michael201529842 Trujillo Ana

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A Binary Search on an Indexed Field

1. First go to the middle record of the table and compare values to see if 606147775>328824082.

2. If it is greater, continue checking only from this midpoint to the end. Otherwise continue checking only from the beginning to the midpoint

3. Then go to the midpoint of this subsection. The process continues until a match is found

This table is sorted by SSN

Indexing can aid in querying efficiency using algorithms such as binary search (1/2,1/2 again) vs. a linear search (1 at time from top to bottom). A binary search cuts the processing time significantly for large databases

ssn lname fname123456789 Sommer Martín139555002 Suyama Michael157745969 Lebihan Laurence178301771 Berglund Christina201529842 Trujillo Ana227776183 Moos Hanna257436001 Citeaux Frédérique290951508 Callahan Laura328824082 Moreno Antonio371616449 Fuller Andrew419975418 Dodsworth Anne474621100 Leverling Janet536370683 Hardy Thomas606147775 Anders Maria684995818 Peacock Margaret774094122 King Robert874775203 Davolio Nancy988544806 Buchanan Steven

Find name of student for ss#606147775

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Indexing vs. Sorting

Sorting your table & saving permanently changes the record order.. Use an index instead.

ssn lname fname123456789 Sommer Martín139555002 Suyama Michael157745969 Lebihan Laurence178301771 Berglund Christina201529842 Trujillo Ana227776183 Moos Hanna257436001 Citeaux Frédérique290951508 Callahan Laura328824082 Moreno Antonio371616449 Fuller Andrew419975418 Dodsworth Anne474621100 Leverling Janet536370683 Hardy Thomas606147775 Anders Maria684995818 Peacock Margaret774094122 King Robert874775203 Davolio Nancy988544806 Buchanan Steven

ssn#606147775 is associated with record 14

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From Tables to a Relational DatabaseFrom Tables to a Relational Database We have carefully looked at tables in our database

how to set them up, define fields etc. The real advantages of a DBMS however are in their ability to relate information.

Thus far we have customer names on one list and transactions on a separate list. How do we match a customer’s name to specific transaction?

We need a way to relate these two tables to extract useful information. We can relate these two tables by matching the account numbers.

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One to Many RelationshipOne to Many Relationship

Customers: Tableacct# ssn lname fname address city state zipcode

456 123456789 Sommer Martín 5400 E. Broad ST Reynoldsburg OH 43213543 139555002 Suyama Michael 4110 Old Redmond Rd. Worthington OH 43201544 157745969 Lebihan Laurence 342 S. Drexel Bexley OH 43209999 123456789 Sommer Martín 5400 E. Broad ST Reynoldsburg OH 43213

1112 178301771 Berglund Christina 707 Oxford Rd. Columbus OH 432222456 201529842 Trujillo Ana 7 Houndstooth Rd. Marysville OH 42001

Acct#/Account No. is the Foreign Key

Account# date transaction$456 4/1/1999 $1,231.39544 4/1/1999 $3,366.82

2456 4/2/1999 $2,301.683064 4/2/1999 $5,087.664456 4/3/1999 $12,838.425323 4/3/1999 $167.805566 4/4/1999 $641.92456 4/9/1999 ($1,186.26)544 4/9/1999 ($3,243.43)

1112 4/11/1999 $159.664456 4/12/1999 ($12,367.91)

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A Foreign Key is a field that defines the relationship between 2 tables:

A Foreign Key is a field that defines the relationship between 2 tables:

A valid foreign key must have all of the properties listed below:

1. Must be a primary key (unique) in at least one of the tables

2. The field names on each table do not have to match as long as the information is the same. Fields with the same name does not necessarily mean they are the foreign key.

3. The related fields must be the same data type (number, text etc)

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Walkthrough: Establishing relationshipsWalkthrough: Establishing relationships

Foreign Key: acct#/Account#

Primary Key on Accounts table: acct#

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Once Relationships are established you can gather information from one or more tables to answer questions like:

Once Relationships are established you can gather information from one or more tables to answer questions like:

Create a list of account numbers and owner names and total transactions

What are the total deposits made by accounts starting with 5?

What is the total balance of all accounts held by Jane Doe ?

These requests are known as Queries

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To extract information from the Database use a Query which is a “question” or “request”

The query is not the data that results but a set of instructions specifying how specific records or combinations of records should be extracted - it lets the user:

prepare lists, sort, filter choose records to met specific criteria do calculations on the data Summarize data by a specific grouping match up the data to related information

“Objects”: Queries

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Walkthrough: A Simple Query Walkthrough: A Simple Query

Design:

Create a query to list the first name, last name and transaction amount for each transaction

We will spend the next 1-2 weeks learning, in greater detail, how to use the query tool.

Dynaset Result:

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Walkthrough: Setting up a formWalkthrough: Setting up a form

A form is not data that results but a set of instructions specifying a screen view format of the data. These forms are designed to simplify data display, inputting and editing.

“Objects”: Forms

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The type of text formatting Report & Page headers, footers, titles Which data fields (from tables, queries

and/or calculations) to be used Sorts, Filters, Groupings of fields

Walkthrough: Setting up an AutoReport

A report is not the data that results but a set of instructions specifying the format of written output. Reports allow users to vary :

“Objects”: Reports

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Sample

Report:

Transactions

by Customer

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Programmed instructions updating tables/queries from inputs

customer address account balance

retrieving data from other sources performing tasks if a certain criterion is met

monthly bank statement balance > 20000

send letter offering estate planning service

“Objects”: Macros &Modules

This course will not cover the Macros & Modules - we can refer you to more Advanced books on Access & Visual Basic

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A Review of Database TheoryA Review of Database Theory

Information is stored in objects known as tables consisting of records or related information categorized into fields. A field that uniquely identifies a table is known as a

primary key field Tables can be related to each other using valid

foreign key fields. Queries, Reports, Forms are objects which can

be created using the data on tables to dynamically extract/display information in a specified format.