Using MySQL Enterprise Data Masking and De-Identification General-Purpose Masking Functions mask_inner()  and  mask_outer()  are general-purpose functions that mask parts of arbitrary strings based on position within the string: • mask_inner()  masks the interior of its string argument, leaving the ends unmasked. Other arguments specify the sizes of the unmasked ends. mysql>  SELECT mask_inner(’This is a string’, 5, 1); +--------------------------------------+ | mask_inner(’This is a string’, 5, 1) | +--------------------------------------+ | This XXXXXXXXXXg | +--------------------------------------+ mysql>  SELECT mask_inner(’This is a string’, 1, 5); +--------------------------------------+ | mask_inner(’This is a string’, 1, 5) | +--------------------------------------+ | TXXXXXXXXXXtring | +--------------------------------------+ mysql>  SELECT mask_outer(’This is a string’, 5, 1); +--------------------------------------+ | mask_outer(’This is a string’, 5, 1) | +--------------------------------------+ | XXXXXis a strinX | +--------------------------------------+ mysql>  SELECT mask_outer(’This is a string’, 1, 5); +--------------------------------------+ | mask_outer(’This is a string’, 1, 5) | +--------------------------------------+ | Xhis is a sXXXXX | +--------------------------------------+ • mask_outer()  does the reverse, masking the ends of its string argument, leaving the interior unmasked. Other arguments specify the sizes of the masked ends. mysql>  SELECT mask_inner(’This is a string’, 5, 1, ’*’); +-------------------------------------------+ | mask_inner(’This is a string’, 5, 1, ’*’) | +-------------------------------------------+ | This **********g | +-------------------------------------------+ mysql>  SELECT mask_outer(’This is a string’, 5, 1, ’#’); +-------------------------------------------+ | mask_outer(’This is a string’, 5, 1, ’#’) | +-------------------------------------------+ | #####is a strin# | +-------------------------------------------+ By default,  mask_inner()  and  mask_outer()  use  ’X’  as the masking character, but permit an optional masking-character argument: Other masking functions expect a string argument representing a specific type of value and mask it to remove identifying characteristics. The examples here supply function arguments using the random value generation functions that return the appropriate type of value. For more information about generation functions, see Generating Random Data with Specific Characteristics. Special-Purpose Masking Functions Note 1578