DATA BASE
It is an
organized list of data (information) that can be queried to find information
quickly and easily based on a chosen reference point such as a last name or a
social security number.
Access is a
RDBMS that you can use to store and manipulate large amounts of information.
A Relational
Database is a database, which consists of Tables of related information that
are linked together based on a key field.
ELEMENTS OF ACCESSES
An
access is an object-oriented program. It has the following objects.
1.Database
Window
2.Tables
3.Queries
4.Forms
5.Reports
6.Macros
7.Modules
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Data
Type
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Description
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Text
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It can store 255 alphanumeric characters, used for storing data
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Memo
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It can hold up to 64,000 characters
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Number
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It is used for calculations, can consist of numerical digits
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Date/ Time
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Stores a date or time. Consists of 8 bits
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Currency
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It is used for monitory values. Consists of 8 bytes.
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Counter
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It is numeric value that automatically increment for each record
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Yes/ No
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Stores Boolean values
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OLE Object
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Stores pictures, graphs and
other binary data. Can consists of 128 MB
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DATA VALIDATION
It helps to reduce the number of
data entry errors, which occur when a large amount of data is being entered
into a database. Access provides a basic level of data validation with the
validation rule property for each field. Assuming that only local phone numbers
will be entered in the field, the first step is to limit the field size to
seven digits. Position the cursor in the filed size panel, and replace the
field size of 50 characters with 7 characters.
Uses of MS- Accesses
It is a Relational Database. It
helps us to collect information in tables. i.e. collection of rows and columns.
Then we can sort it, print it or scroll through. It allows us to create forms
in user-defined fashion. Apart from forms, reports are created which can
include subtotals, averages, and some other computations. If we need to view
data directly or depending on some condition also, queries is applied.
Queries
Ø
By using queries we can view, change and analyze
data in different ways. You can also use them as the source of records for
forms and reports.
Ø
You can bring together data form multiple tables
and sort it in a particular order.
Ø
You can perform calculations on groups of records
Ø
You can calculate a sum, count, or another type
of total and then group the results by two types of information – one down the
left side of the datasheet and another across the top.
The query window is divided in to
two halves. The top panel contains the list of all the fields in a table and in
the bottom panel the criteria for the query are entered this panel is called
the design grid. This design grid having 5 rows.
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Field
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Specifies the fields to be included in the
query
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Table
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Specifies which table does the above field
belong to.
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Sort
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Specifies the manner in which the query has
to be sorted.
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Show
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Specifies whether to display the field or
not
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Criteria
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Specifies the criteria of the records to be
shown.
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PRIMARY KEY
Ø
It is the field, which identifies a record. The entry done into this field is unique. It
cannot be same for the two records.
Ø Primary
field of one table appearing as a normal field in some another table is called
a Foreign Key Field. If there is a entry in the Foreign key field then there
has to exist a corresponding entry in
the primary key field.
LOGICAL OPERATORS
Ø
Logical and Logical OR operators
Ø
The AND operator is used when two criteria’s
have to be entered into a single field. It returns the result only when the
single field satisfies both the condition.
Ø
The OR operator is sued for matching any of the
values specified in the criteria. It returns the result even if the single
field satisfied any one of the criteria.
RELATIONSHIPS IN DATABASE
In MS- Accesses Database, there are
3 types of Relations
1.One to One Relationship
2.Many to One Relationship of One to Many Relationships
3.Many to Many Relationships
FORMS
Ø
In a table, numbers of records are displayed at
a time. But if the table has many fields then it may not be possible for a user
to view all of them. The screen may be too small to fit it. The user may have
to scroll horizontally or vertically to view the rest of the fields / Records.
Ø
In forms the data can be displayed as per the
users requirement. The records are generally displayed one at a time. The
fields can be arranged as the user wants it. Pictures can be added to a form.
The display and contents of the form is controlled fully by the user.
FORMS - 2
In forms there are three views
1.
Design
2.
Data Sheet
3.
Form
The data sheet
view shows many records whereas form view displays single record. You can
toggle between these three views using the View Tool.
Type of the Forms
1.The
design view
2.Form wizard
3.Auto form columnar
4.Auto form tabular
5.Auto form data
sheet
6.Chart wizard
7.Pivot table wizard
REPORT
The data shown in table, Query and forms are meant for
displaying it on screen, but when you take out the printouts or the Hard copy
it is known as Reports. In the database window the open button is replaced by the
preview button, when you click the report tab. Reports can be viewed either in
print preview mode or design mode. Data cannot be edited in the reports. The
reports preview shows how the data will appear on taking out the printouts.
