MASK_FIRST_N

Description

The MASK_FIRST_N function is mainly used to mask the first N bytes of data to protect sensitive information, and is commonly used in data anonymization scenarios. Its behavior is to replace a uppercase letter with X, a lowercase letter with x, and a number with n in the first N bytes.

Syntax

MASK_FIRST_N( <str> [, <n> ])

Parameters

Parameter	Description
<str>	String that need to be masked
<n>	Optional Parameter, limit data masking to only the first N bytes, default to masking the entire string

Return Value

Returns a string after masking uppercase character, lowercase character and lnumeric character in first N bytes. Special cases:

• If any Parameter is NULL, NULL will be returned.
• Non-alphabetic and non-numeric characters will do not masking

Examples

select mask_first_n("1234-5678-8765-4321", 4);

+----------------------------------------+
| mask_first_n('1234-5678-8765-4321', 4) |
+----------------------------------------+
| nnnn-5678-8765-4321                    |
+----------------------------------------+

select mask_first_n("1234-5678-8765-4321", null);

+-------------------------------------------+
| mask_first_n('1234-5678-8765-4321', NULL) |
+-------------------------------------------+
| NULL                                      |
+-------------------------------------------+