Computers-MS Access

MS Access

MS Access is a powerful database management system that functions in the windows environment and allows to create and process data in a database.Some of the key features are:
Data entry and update:Access provides easy mechanisms for adding,changing and deleting data,including the ability to make mass changes in a single operation.
Queries:Using Access,allows to ask complex questions concerning data in the database very easily and receive instant answers.
Forms:Access helps to produce attractive and useful forms for viewing and updating data.
Reports:Access contains a feature to create sophisticated reports easily for presenting data.
Database is a collection of data organized in a manner that allows access,retrieval and use of that data.Access allows to add,change and delete data in the database.
A database consists of a collection of tables in Access.The rows in the tables are called records.A field contains a specific piece of information within the record.
Starting Access
Click on Start button.
Click on All Programs.
Click on MS Office.
Click on MS Access.



Understanding Access Window
Title bar:It shows the name of the displayed database.
File tab:It displays file commands as New and Open.
Quick Access Toolbar:It displays quick access buttons to Save,Undo and Redo commands.
Status bar:displays information about the current object or view.
Create a New Table
By entering data into a table,you can start a database.Tables consist of columns and rows that intersect to form cells for holding data.Each row is considered to be a record in a table.You can use columns to hold fields in a table.
Click on create tab on the ribbon.
Click on table button.
Access opens a new table in datasheet view.
Double-click the column header to create a field name.
Type a name for the field.
Press Enter key from keyboard.
Click on next column.
Select the data type for the field.Eg. select Text,if you want to add Name field.
If you want to change the data type,click on the arrow button andame column.
change the data type according to your need.
After selecting the data type,its properties will be displayed in the lower pane.
After selecting the data type,press the TAB key to move the insertion point to the description column.
Press TAB key again to move to the Field Name column in the second row.
Type the text in field name column.
Press the TAB key to move to the Data Type column.
The word ‘Text’ is currently displayed in that field.
Press the TAB key to move the insertion point to Description column,if you want the data type as text.
Type the text for the description column.
Repeat steps to make the remaining entries in the table to complete it.

Setting a Primary Key
A primary key is a key that differentiates the records in a file.The data stored in a key field contains data that is unique to a specific record.A student record,example,would use Roll number as a key field because it uniquely identifies each student.
In each new table that you create,you’ll want to set one field as the primary key.Access uses this key to relate this table’s records to those in another table.
Choose the field that you want to set as the primary key.
Click on the primary key button.
The field will be set as the primary key,indicating by a small key in the field of selector column.To remove it,select the primary key field and click on the primary key button again.
Save a Table
After creating a new table,it must be saved to make it a permanent part of the database.
Right click on the table’s tab.
Click on Save.
Type a name for the table.
Click on OK.
The table remains open,and its new name appears on its tab.
Insert and Delete fields
New fields can be inserted and existing removed into a field list.A new row appears in the grid-above the one selected.
Steps-
Select the field where you want new field should appear above.
Click on design tab.
Click on insert rows.
A new row appears above the selected row.
Type a field name and choose a field type.

Select a field you want to delete.
Click on design tab.
Click on delete rows.
The row will be deleted,along with any data that the fields have.

Understanding Data Type
Each field has a data type that defines what you can store in it.Data entry is restricted to valid entries for the type you choose,which helps to prevent data entry errors.Example,you cannot enter letters in a field set to Number,and you must enter valid dates or times in a date/time field.

Text:This is a general purpose field containing any data.It has a limit of 255 characters and cannot be used for numeric calculation.
Memo:This has a limit of 63,999 characters;used for detailed,descriptive fields.
Number:This type stores numeric data that you can use in calculations.It can also hold symbols,as decimal points and commas.
Date/Time:This type only stores numbers representing valid dates and times.
Currency:Stores currency data that you can use in calculations.
Auto Number:stores a sequencial number for each record.
Yes/No:The value -1 represents Yes,and the value 0 represents No,but the field can be formatted to display values as
True/False or Yes/No.
OLE Object:stores objects created in another application-as Word or Excel-that you can link to or fix in an Access table.
Hyperlink:You can link to websites,email addresses,files on your computer,files on any other location.
Attachment:You can attach data files.

Change Data Type

The data type of a field can be changed anytime to better represent data.Field types should be set before entering data into table,field type can be changed anytime.

Click on the down arrow to ope the Data Type list for the field.
Click on new type.
To save the changes to the table,click on save.
Click on yes to allow the deletion of records that violate the new field type’s rules.
No can be clicked to abandon the change.

Rename a table

A table can be renamed at any time.Access automatically updates all references to the table throughout the database.The table must be closed in order to rename it.

Right click on the table name in the navigation pane.A short cut menu appears.
Choose rename from the shortcut menu.The table name appears in edit mode.
Type the new name for the table and press enter key from the keyboard.
The new name appears on the table.
Click on the table name in the navigation pane.
Click on Home tab.
Click on delete button from record group.
A confirmation dialog box opens.
Click Yes.
The table will delete.

Adding Records to a table

The first step is to create a table by building the structure and saving the table.The second step is to add records to the table.The table must be open so that the records can be added to the table.The table displays in datasheet view.In datasheet view,the table is represented as a collection of rows and columns called a datasheet.

Double click on table in the customer:database window.
Type the customer id in the first customer id field.
Press the tab key to complete the entry for the customerid field.
Type the following entries by pressing the tab key after each one to complete the record.
After typing the last entry,press the tab key.
The insertion point comes to the customerid field in the second row.
Add the remaining records by following the same steps you used to add first record.
Click on save,to save the changes.

MS Power Point

Powerpoint is the component of microsoft office.It combines text,cli art,drawing features and other objects to create self running or interactive display.
Powerpoint offers several advantages-
1.It navigates easily through the presentation.
2.It allows information from other sources to be available for presentation.
3.The computer uses the capability of its color to its full extent.
4.It utilizes multimedia effect.
5.Projection equipment is not required.
Getting started with MS Powerpoint:
Click start.
Click Programs.
Click MS Powerpoint.
Click Blank presentation.
Enter title of your presentation.
Click insert.
Click chart.
Or click pictures.
Or click on MS Word Table.
In word table enter the number of columns and number of rows.Type contents in word table.
Changing the case of the text:
Click format.
Select change case
Select text for the changing the case.
Click OK.
To display the slide,select slide sorter option from View menu.

Delete a slide
Select the slide to be deleted.
Select delete slide from edit menu.

Adding clip art pictures

Click insert.
Select clip art.
Select the picture.
Click on insert.
Selected picture is inserted in slide.

Saving Presentation:
From File menu select save as option.
Save as dialog box is displayed.
Click on Save button.

Know Computer Security

Computer Security

Now-a-days computers are becoming a reliable source to create,store and manage critical information.It is also crucial that users take measures to protect their computers and data from loss,damage,and misuse.For example,a company must ensure that information,such as credit records,employee and customer data and purchase information are secure and confidential.
Computer security risk is a term known for any event or action that could be harmful for a computer hardware,software,data information or processing capability.Some breaches to computer security are accidental while others are planned.Any illegal act involving a computer is generally referred to as a computer crime.The term cybercrime refers to online or internet-based illegal acts.
The following sections describes some of the more common computer security risks and safeguards,you can take to minimize or prevent their consequences.
Computer Viruses
Virus is a potentially damaging program in a computer,which negatively effects or infects your computer without your knowledge and alters the working of the computer.More specifically,a computer virus is a segment of program code from some outside source that implants itself in a computer.Once a virus is in your computer,your files and operating system may be damaged.
The increased use of networks,the internet and email has accelerated the spread of computer viruses.With these technologies,computer users easily can share files and any related viruses.Viruses are activated on your computer in three basic ways:
(1)Opening an infected file
(2)Running an infected program
(3)Booting the computer with an infected floppy disk in the disk drive.
The most common way of virus in a computer is through the attachment in an email.Before you open or execute any email attachment,you should ensure that the email message is from a trusted source.A trusted source is a company or person you believe will not send you a virus infected file knowingly.You should immediately delete any email received from an unknown source without opening or executing the attachment.Thus you can protect your computer against viruses if you follow the precautionary measures.
Viruses in computer are not generated accidentally but are programmed intentionally by a programmer known as a virus author.Some virus authors find writing viruses a challenge.Others write them to cause destruction.Writing a virus program usually requires significant programming skills.Some viruses are harmless ranksthat simply freeze a computer temporarily or display sounds or messages.The music bug virus,example,instructs the computer to play a few chords of music.Other viruses destroy or corrupt data stored on the hard disk of the infected computer.If your computer acts differently from usual,it may be infected with a virus.
Today,viruses pose as serious threat to the safety of a computer.Currently,more than million known virus programs exist with an estimated 6 new virus programs discovered each day.
Though there are numerous variations,3 main virus types known to exist are,boot sector,file and macro.
A boot sector virus also known as a system virus,executes when a computer boots up because it resides in the boot sector of a floppy disk or the master boot record of a hard disk.When you leave a floppy disk in the floppy disk drive and boot up the computer,the computer attempts to execute the boot sector on the disk in drive A.The hard disk of a computer can be infected by any virus on the floppy disk’s boot sector even if the disk is not the boot disk.

Computers-Input and Output devices

Input and Output Devices

We know about different parts of a computer.All these parts are either Input or Output Device.
Example:
Step1:Take some mangoes.
Step2:Cut them.
Step3:Put them in the juicer.
Step4:Switch on the juicer for 5-6 minutes.
Step5:Switch on the juicer.
Step6:Pour out the juice.

The mangoes are input.
The juice we get is the output.
Device means machine(Here juicer is the device).
A computer needs information and Data to work.
In the same way all characters,numbers and words given to the computer are called Input.
The result given by the computer is called Output.
Input devices transfer data and information into the computer.
Output devices give the desired results out of the computer.