A data type defines the kind of data that can be stored in a field.
For example: - A student's name contains text. - A student's date of birth contains a date. - A student's marks contain a number.
Therefore, we should select the correct data type for each field.
| Data Type | Use | Example |
|---|---|---|
| Short Text | Stores text and numbers that are treated as text. Even if numbers are entered in a text field, they are treated as text. | Rahul, Ranchi, 9999999999 |
| Number | Stores numerical values. | 10, 85, 2500 |
| Date/Time | Stores dates and times. | 15/08/2011, 10:30 AM |
| Currency | Stores monetary values. Currency is useful for Fees, Salary, Price, Expenses, etc. | ₹2500 |
| AutoNumber | Automatically generates unique numbers whenever a new record is added. | 1, 2, 3, 4 |
| Yes/No | Stores two possible values. | Yes/No |
NB: Choose the correct data type according to the type of information stored in the field.
Design View is used to create or modify the structure of a table.
In Design View, we specify: - Field Name - Data Type - Description - Set various Field Properties
NB: We will study Primary Key in greater detail in Unit 4.
Field properties appear in the lower part of the Table Design View. They control how data is stored, displayed, or entered in a field.
| Property | Use |
|---|---|
| Field Size | Defines the maximum number of characters or digits that can be stored in a field. (1 to 255) |
| Format | Controls how data appears when displayed or printed. For example, dates can be displayed in different formats. |
| Input Mask | Provides a pattern for data entry to ensure consistency. |
| Caption |
Sets an alternate name for the field label shown in forms or reports
instead of the field name. Example: Field Name: Student_Name → Caption: Student Name |
| Default Value |
Automatically inserts a preset value when a new record is created.
Example: Country = India |
| Validation Rule |
Specifies a condition that the entered data must satisfy.
Example: >= 0 |
| Validation Text | Displays a custom message when data violates the validation rule. |
| Required | When set to Yes, a value must be entered in the field. |
| Allow Zero Length | Permits empty strings (Yes/No). |
Meaningful names such as Students, Teachers, Fees, etc. make the database easier to understand and manage.
We must avoid names such as Table1, Table2, etc.