Mask

mask_inner(str, margin1, margin2 [, mask_char]) 
mask_outer(str, margin1, margin2 [, mask_char])

Function

The mask_inner and mask_outer functions are used to replace parts of a string, typically to hide sensitive information such as passwords, phone numbers, etc. The mask_inner function retains the characters at both ends of the string with lengths margin1 and margin2, while replacing the middle part with a specified mask character (default is 'X'). The mask_outer function masks the characters at both ends of the string with lengths margin1 and margin2, retaining the middle part.

Parameter Description

• str: The original string to be processed.
• margin1: The number of characters to retain or mask on the left end.
• margin2: The number of characters to retain or mask on the right end.
• mask_char (optional): The mask character used to replace the middle part of the string, default is 'X'.

Return Value

Returns the processed string.

Usage Example

-- Example 1: Hide the middle four digits of a phone number
SELECT mask_inner('13812345678', 3, 4);
-- Return result: 135XXXXX876

-- Example 2: Retain the front and back parts of an email address, hide the username part
SELECT mask_outer('alice@example.com', 5, 0);
-- Return result: XXXXX@example.com

-- Example 3: Hide the middle eight digits of a credit card number
SELECT mask_inner('1234 5678 9012 3456', 4, 4, '*');
-- Return result: 1234 **** 9012 3456

-- Example 4: Hide the middle ten digits of an ID card number
SELECT mask_inner('11010519850605003X', 2, 10);
-- Return result: 11XXXXXXXXX03X

By the above example, you can flexibly use the mask_inner and mask_outer functions according to actual needs to protect users' privacy information.