dbms

Database Management Systems(DBMS)

Anil [email protected]

Dept. of Computer Science, University of Ruhunahttp:// www.ruh.ac.lk / dcs /

CCCT – Dept. of Computer Science University of Ruhuna http://www.ruh.ac.lk/dcs/

Learning Outcomes

• Understand the need for database management

• Understand the Database Concepts

• Plan, design and use Microsoft Access databases

• Learn to use SQL for data definition and data manipulation.


Introduction to Database Concepts

• Why need database management ?

?


Branch BranchMobile

ATM users

ATM users

Bank


File Processing System

• Individual applications maintain own private data files.

• Leads to data duplication (redundancy).

• Data is in different formats• Inflexible • Management is very difficult


What is a Database?

A database is an organized collection of related data stored in a common pool that can be accessed by many users for many purposes.


Student database

• Course name file• Student name file• Marks file• …

A database is a group of related files


What is a Database?

• Data collection may be . . .

Electronically Collected Manually Collected


Key Features of a database

The data is

• input (stored) only once• Organized in some fashion• Accessible effectively and efficiently


What is a Database Management System (DBMS)?

• A software system that provides an efficient and convenient environment for

• Storing• manipulating (Change, Delete …)

• accessing data in the database


Overview of a DBMS

DBMS Data-bases

Data-bases

Modify /Retrieval

(Command)

Results

Users


Thousands of commercial and non commercial DBMS available in the world

Eg:• MS Access• Oracle• MS SQL Server• MySQL• PostgreSQL• …


Advantages of using DBMS

• Data duplication and storage space wasting can be avoided

• Data can be shared• Unauthorized access can be

restricted• Recovery from failures


Characteristics of Modern DBMS

• Query processing• Transaction management• Concurrency control• Database recovery• Database security and authorization• Distributed databases


Disadvantages of using DBMS

• cost of extra hardware • cost of entering data • cost of training people to use

DBMS • cost of maintaining DBMS• complex


Controlling & Maintaining a Database

Database Administrator (DBA)

Database


Duties of the Database Administrator

• Installing and upgrades of database software• Performance tuning• Backup and recovery strategies • Start the database & shutdown the database• Monitoring the database• Give and drop database access to the users• Consultation with developers


What is a relational database? • Stores data inside tables• Tables can be joined by a common

field

relational database


Database Building Blocks

• FieldField represents an attribute, or a characteristic or a piece of information

• Record A record is a group of related fields.

• File/TableA collection of related records


What is a Table?

a collection of records about a specific topic.

Eg: a table about collection of Addresses and Contac Numbers


What is a Record?

A row in a table

A record (a row)


What is a Fields?

A column in a table

A Field (a column)

Microsoft Access


What is Access ?• Database management system (DBMS)

• Desktop software that defines a database,

stores the data, supports a query language,

produces reports, and creates data entry

screens.


Object Types of MS Access database• Table

• Query

• Form

• Report

• Macro

• Module


What is a Table in MS Access?A Table allows the user to store a collection of data about a specific topic. This is the fundamental structure in the Access Fields (Columns)

Records (Rows)


What is a From ?A form allows a user to add , edit or delete data within the corresponding table.


What is a Report ?A report is an efficient way to output your data in a printed format in the way you want it.


What is a Query ?A query allows the user to view, change, and analyze data in different ways like combining data from multiple related tables to create a user’s own view.

Select

Who are in Matara


What is a Macro ?

A macro is a set of instruction that automates a task you need to do often. When you run the macro, Access carries out the actions in the macro.


What is a Module ?

In the rare cases where programming is necessary, you can write modules, like macros, modules allow you to automate and customize Access.


Starting MS Access


Creating a Database


Opening an Existing Database


Creating Tables

• Using Wizard • Using Design View


What is a Wizard?A Microsoft Access tool that asks you questions and creates an object according to your answers.

Wizard presents a series of dialog boxes with group of options, which you can choose .

For example, you can create tables, queries, forms, reports, or data access pages by using wizards.


What is a Design View?

• Allow you to create your own. • It can be more flexible and

versatile than wizard-generated


Creating a Table Using Wizard


Entering Data in a table


Exercise

1 to

2 questions in

Assignmen

t one


What is a table structure?

A data structure is a specialized format for organizing and storing data.


What is a table structure?

App_No Reg_No Name Address

145 CCCT/06/03/001 Abayagunawardana W.H.S. Kottagoda

105 CCCT/06/03/004 Dayananda P.M.M.N. Weligama

120 CCCT/06/03/005 Dhammika Upul P. Habaraduwa

129 CCCT/06/03/006 Gunarathna K.P.S.T. Galle


Data Types of Microsoft Access

Data type of a field determines the kind of data the field can store. Every field must have a defined data type .



• Text• Memo• Number• Date/Time• Currency• Auto Number• Yes/No • OLE objects



Text : This field stores text and numbers and any combination of characters. Can contain up to 255 characters

Eg: Name : Text(25)

Memo : A passage of information text or notes that can contain 64000 characters

Eg : Qualification : Memo



Number : This can contain integer or decimal numbers

Eg : Salary : Number

Date/Time : Used for date or time values

Eg: BithDate : Date/Time

Currency : Used for monetary values

Eg : Salary : Currency



Yes/No : A Yes/No values , represent a logical true or false state

Eg : Permanent : Yes/No

Auto Number : A unique record number, automatically inserted begins with 1



OLE Object : Use this type to link pictures, audio, video, or other large objects

Eg : Picture :OLE Object

Hyperlink : Use this type to store the location of a file on your computer, a local network, or the world

wide web

Eg : NetAddress : Hyperlink


Field Name Field Type Field Size

App_No

Reg_No

Name

Tel_No

App_No

Reg_No Name Tel_No

145 CCCT/06/03/001 Abayagunawardana W.H.S. 041-2259154

105 CCCT/06/03/004 Dayananda P.M.M.N. 041-2250622

120 CCCT/06/03/005 Dhammika Upul P. 041-2223584

129 CCCT/06/03/006 Gunarathna K.P.S.T. 091-2246786

Number

Text

Text

Text

14

25

11

Exercise

Define a

suita

ble

table str

ucture


Field Properties of a Table

• Formats• ValidationRule and ValidationText• Default Value• Input Mask• Caption• Indexed

Formats

• You can use the Format property to customize the way numbers, dates, times, and text are displayed and printed.

Example– Medium Date : 3-Apr-93.– Long Date : Saturday, April 3, 1993.


ValidationRule

• You can use the ValidationRule property to specify requirements for data entered into a record, field, or control. When data is entered that violates the ValidationRule setting, you can use the ValidationText property to specify the message to be displayed to the user.


Default Value

• Sets or returns the value of an object


Caption

Specify a label other than field name for Forms and Reports


Indexed

Speeds up searches


Input Mask

• You can use the InputMask property to make data entry easier and to control the values users can enter



Input mask syntax


Examples


Exercise

3 to

4 questions in

Assignmen

t one


Field Name Data Type Length Other Properties

Name

Address

Tel No

Work Place

Designation

Married

Date MakeOut

Field Name Data Type

Length

Other Properties

Name Text 25 Required --> Yes

Address Text 50

Tel No Text 11 Input Mask --> 000-0000000

Work Place Text

Designation Text 25 Input Mask --> >L<???????????????????????

Married Yes/No Default Value --> FALSE

Date MakeOut

Date/Time Format --> Long Date



Creating Tables Using Design View


Importing Data to Your Database

Import data from the Employee_Personal_Division Excel file and create a table called Personal Division in your database.


Link Data from another data Source

Link your database with the Employee_Personal_Division Excel file and name it as “Linked table”


• Open your Linked table and enter following data to end of your table

Emp_No

Name Date_Joined Pay_tax

OT_Hours

Des_Code

E044 Gunasekara K. 02/05/2000 No MGR

• Open your Employee_Personal_Division Excel file and observe.


Setting a Primary Key


Entering Data in a table 2 The table opens in Datasheet view. Type your data under the relevant fields

1 Double-click the table in the database window


What is a Primary Key ?

An attribute that uniquely identifies each row in a table


What is a Primary Key ?

One and only E002 value in the Emp_no field

Primary Key field


Setting a Primary Key


What is a Relationship ?

Association between entities (Tables)

=


Referential integrity

Referential integrity is a system of rules that uses to ensure that relationships between records in related tables are valid, and that you don't accidentally delete or change related data.


Rules apply when you use referential integrity

• You can't enter a value in the foreign key field of the related table that doesn't exist in the primary key of the primary table.

• You can't delete a record from a primary table if matching records exist in a related table.

• You can't change a primary key value in the primary table, if that record has related records.


Primary key

Foreign key

Parent tableChild table

Package Table

Customer Table Table


Cascade Update Related Fields

• If you select the Cascade Update Related Fields check box when defining a relationship, any time you change the primary key of a record in the primary table Microsoft Access automatically updates the primary key to the new value in all related records.


Cascade Delete Related Records

• If you select the Cascade Delete Related Records check box when defining a relationship, any time you delete records in the primary table, Microsoft Access automatically deletes related records in the related table.


What is a Query?

• A query permits you to select records from your database tables that meet certain conditions or criteria.

• Queries can make lists from one or more tables

• You use queries to view, change, and analyze data in different ways.


Create a simple select query with a wizard


Query Design Grid


operators used in MS Access

Option Description Example

+ Addition [Basic Salary]+2200

- Subtraction

* Multiplication

/ Division

Arithmetic Operators


Comparison OperatorsOption Description Example

= Equal = Sarath

< Less than

<= Less than or equal to

> Grater than > 1000

>= Grater than or equal

<> Not Equal <> Matara

Between Between two Values Between 100 and 200

In Within a List of values In (Hambantota Matara, Galle)

* Any Character 041-22*

Like Match a Pattern Like Ruw*


Option Description Example

Logical Operators

AND Both elements of an expression must be true

NOT The expression must evaluate as false

OR At least one element of an expression must be true


Creating a Query by Hand (Design View)


Structured Query Language (SQL)

Structured Query Language (SQL) is a standard query language for managing relational databases. SQL allows users to define the data in a database and manipulate that data.


Data Definition Language (DDL)

• The data definition language is that (DDL) part of a query language responsible for defining and modifying the structure of the database.

• The principal DDL statements in SQL are:

• CREATE TABLE• ALTER TABLE• DROP TABLE• Etc…


Data manipulation Language (DML)

• Part of a query language responsible for manipulating database objects.

• Some DML commands are:• SELECT• INSERT• UPDATE• DELETE


Creating a Table Using SQL

CREATE TABLE students( Name text(20),

Address text(20),Marks number );

Name Address Marks

Students


Inserting data using SQL

INSERT INTO studentsVALUES ('Bimal S.K.','Matara',68);

Name Address MarksBimal S.K.

Matara 68

Students


What is a Form?

Forms provide a convenient way to • enter data• view data

in a database.

• Forms also restrict access to the specific fields in the table


Creating Forms

• Creating Auto Forms • Creating Forms with a wizard • Creating Forms in Design View


Creating Auto Forms

• Either columnar, tabular, or datasheet layout

• With AutoForm, you select one record source and

• AutoForm creates a form that uses all the fields from the record source


Creating Auto Forms


Creating Forms with a wizard

The wizard asks you detailed questions about the • record sources• Fields• Layout• format

you want and creates a form based on your answers


Creating Forms with a wizard


Creating Forms in Design View


Create a Command Button with a Wizard

You use a command button on a form to start an action or a set of actions


Create a Command Button with a Wizard


Working with Reports


Reports

A Report is an effective way to present your data in a printed format

Most of the information in a Report comes from an underlying table, query, or SQL statement which is the source of the Report’s data.


Auto Reports

AutoReport creates a report that displays all fields and records in the underlying table or query.


Create following Interface for your ABC Company database using a form Design View


• Import data from the Employee_Personal_Division Excel file and create a table called Personal Division in your database.

• Publish data in Designation table with MS Word.

• Publish data in Employee table with MS Excel.


Importing Data to Your Database

Import data from the Employee_Personal_Division Excel file and create a table called Personal Division in your database.


Link Data from another data Source

Link your database with the Employee_Personal_Division Excel file and name it as “Linked table”


• Open your Linked table and enter following data to end of your table

Emp_No

Name Date_Joined Pay_tax

OT_Hours

Des_Code

E044 Gunasekara K. 02/05/2000 No MGR

• Open your Employee_Personal_Division Excel file and observe.


• Data Analyze• Forms with Command buttons• Reports• Link Tables• Import Data tables• Publish Tables with MS Word/Excel• Mail Merge with MS access• Using Help

dbms

Documents

dbms complex ccct

dbms data duplication

failures ccct

data collection

database concepts plan

data manipulation

databasethe data

data definition