Name
The Name is a descriptive identifier for a field that can be up to 128 characters. The names should be descriptive enough that anyone can easily identify them when viewing or editing records. For example, LastName, FirstName, StreetAddress, or HomePhone.
Use the Name edit box to set the field name. Note that the name of the field must be unique among all the field names in the table.
Type
After you name a field, you choose a data type for the data to be contained in the field. When you choose a field's data type, you are deciding:
- What kind of values to allow in the field. You cannot store text in field with the Numeric data type.
- How much storage space SQL Server is to set aside for the data in that field.
- What types of operations can be performed on the values in that field.
The Type dropdown list defines the type of the field data. See SQL Server Data Type and SQL Azure Support Data Type for details.
Size
Define the size of the field.
Scale
Define the number of digits after the decimal point (the scale) for Floating Point data type.
Note: Be careful when shortening the field length as losing data might be caused.
Allow Null
Allow the NULL values for the field.
Note: To set NULL and Empty String as default value, see Setting Other Field Properties.
Key
A Primary Key is a single field or combination of fields that uniquely defines a record. None of the fields that are part of the primary key can contain a null value.