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    Categories: String

    MASK_FIRST_N

    Returns a masked version of a string with the first num_chars characters masked. By default, if you do not provide a mask value, the first four characters are masked.

    Syntax

    MASK_FIRST_N(expression varchar, num_chars int, uc_mask varchar, lc_mask varchar, num_mask varchar) → varchar

    • expression: The string to mask.
    • num_chars: The number of characters to mask.
    • uc_mask: Controls the mask character for upper case letters.
    • lc_mask: Controls the mask character for lower case letters.
    • num_mask: Controls the mask character for numbers.

    Examples

    MASK_FIRST_N example 
    SELECT MASK_FIRST_N('abcd-ABCD-1234')
-- xxxx-ABCD-1234
    MASK_FIRST_N example containing optional mask value 
    SELECT MASK_FIRST_N('abcd-ABCD-1234', 2)
-- xxcd-ABCD-1234
    MASK_FIRST_N example containing optional arguments 
    SELECT MASK_FIRST_N('Aa12-ABCD-1234', 4, 'U', 'u', '#')
-- Uu##-ABCD-1234

    Usage Notes

    By default, upper case letters are converted to X, lower case letters are converted to x, and numbers are converted to n. You can override the characters used in the mask by supplying optional arguments. The second argument controls the mask character for upper case letters, the third argument for lower case letters, and the fourth argument for numbers.