Mask mobile numbers in MSSQL

Masking mobile numbers in MSSQL can be achieved using the SUBSTRING() function to replace certain digits with a mask character. Below is an example of how to implement this:

CREATE FUNCTION dbo.MaskMobileNumber (@mobileNumber VARCHAR(15))

RETURNS VARCHAR(15)

AS

BEGIN

    DECLARE @maskedNumber VARCHAR(15)

    IF LEN(@mobileNumber) = 10

        SET @maskedNumber = 'XXX-XXX-' + RIGHT(@mobileNumber, 4)

    ELSE IF LEN(@mobileNumber) = 11

        SET @maskedNumber = 'XX-XXX-' + RIGHT(@mobileNumber, 4)

    ELSE IF LEN(@mobileNumber) = 12

        SET @maskedNumber = 'X-XXX-' + RIGHT(@mobileNumber, 4)

    ELSE IF LEN(@mobileNumber) = 13

        SET @maskedNumber = 'XXX-XXXX-' + RIGHT(@mobileNumber, 2)

    ELSE IF LEN(@mobileNumber) = 14

        SET @maskedNumber = 'XX-XXXX-' + RIGHT(@mobileNumber, 2)

    ELSE IF LEN(@mobileNumber) = 15

        SET @maskedNumber = 'X-XXXX-' + RIGHT(@mobileNumber, 2)

    ELSE

        SET @maskedNumber = 'Invalid Mobile Number'

    RETURN @maskedNumber

END;

Usage:

SELECT dbo.MaskMobileNumber('1234567890') AS MaskedNumber;

This will output XXX-XXX-7890.

Here are few FAQs:-

1. Why should mobile numbers be masked in a database?

   - Mobile numbers may contain sensitive information, and masking them helps to protect user privacy, especially in scenarios where data is shared or accessed by multiple parties.

2. Can the original mobile number be retrieved from the masked version?

   - Ideally, the masking process should be irreversible to maintain data security. Therefore, the original mobile number should not be retrievable from the masked version.

3. How can I ensure that masked mobile numbers are still usable for certain operations?

   - By retaining some part of the original mobile number, such as the last few digits, you can maintain the usability of the data for operations like identification or verification, while still protecting sensitive information.

4. Are there any legal requirements for masking mobile numbers?

   - Depending on the jurisdiction and the nature of the data being handled, there may be legal requirements or industry standards mandating the protection of personally identifiable information (PII), which includes mobile numbers.

5. Can I customize the masking format to suit my specific requirements?

   - Yes, the provided masking function can be customized to accommodate different formatting preferences or variations in mobile number structures. You can modify the function logic accordingly to meet your needs.