What Would Be a Good Access SQL Data Type for a Phone Number Field?


Larry Thompson

When designing a database, choosing the right data type for each field is crucial to ensure efficient storage and retrieval of information. Access SQL provides various data types to suit different types of data. When it comes to storing phone numbers, it is important to consider the format of the phone number and the operations that will be performed on it.


If you plan on storing phone numbers as text, you can use the VARCHAR data type. This is a variable-length string type that allows you to store alphanumeric characters. However, when using this data type, you need to make sure that you enforce proper validation rules for the phone number format.

For example, if your phone numbers are always in the format “xxx-xxx-xxxx,” you can use a validation rule or a regular expression check to ensure that only valid phone numbers are entered into the field.

Number (Numeric)

If your phone numbers consist only of numeric digits without any special characters or formatting, you may consider using the Numeric data type. This data type allows you to store numeric values with specified precision and scale.

However, when using this data type, keep in mind that arithmetic operations such as addition or multiplication may not be meaningful for phone numbers. It is recommended to perform any mathematical operations on the corresponding text representation of the number rather than directly on the numeric field.

Custom Data Type (User-Defined)

In some cases, neither text nor numeric data types may fully meet your requirements for storing phone numbers. In such situations, you can create a custom user-defined data type specifically tailored for phone numbers.

To create a custom data type in Access SQL, you can use the CREATE DOMAIN statement. This allows you to define a data type with specific constraints and validation rules, such as the format of the phone number and any additional requirements you may have.


CHECK (VALUE LIKE '___-___-____')

In the above example, we create a custom data type called Phone_Number, which is a VARCHAR with a length of 12 characters. The CHECK constraint ensures that the value matches the format “xxx-xxx-xxxx”.

  • Advantages:
    • Enforces specific formatting rules for phone numbers.
    • Provides better data integrity by preventing invalid phone numbers from being stored.
  • Disadvantages:
    • Requires additional effort to create and maintain the custom data type.
    • Might not be supported by all database management systems.


In conclusion, when choosing a data type for a phone number field in Access SQL, consider factors such as the format of your phone numbers and the operations you need to perform on them. If your phone numbers have specific formatting requirements, consider using text or a custom user-defined data type.

On the other hand, if your phone numbers consist only of numeric digits without any special characters or formatting, you can use a numeric data type. Remember to always apply proper validation rules to ensure data integrity.

Note: The choice of the appropriate Access SQL data type may vary depending on your specific requirements and the capabilities of your database management system.

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