條件式動態資料遮罩

您可以在遮罩運算式中使用條件運算式建立遮罩政策，以在儲存格層級上遮罩資料。例如，您可以建立一個遮罩政策，根據該資料列中其他資料欄的值，將不同的遮罩套用至值。

以下是使用條件式資料遮罩來建立並附加遮罩政策的範例，該遮罩政策會修改涉及詐騙的部分信用卡號碼，同時完全隱藏所有其他信用卡號碼。您必須是超級使用者或具有 sys:secadmin 角色才能執行此範例。

--Create an analyst role.
CREATE ROLE analyst;

--Create a credit card table. The table contains an is_fraud boolean column,
--which is TRUE if the credit card number in that row was involved in a fraudulent transaction.
CREATE TABLE credit_cards (id INT, is_fraud BOOLEAN, credit_card_number VARCHAR(16));

--Create a function that partially redacts credit card numbers.
CREATE FUNCTION REDACT_CREDIT_CARD (credit_card VARCHAR(16))
RETURNS VARCHAR(16) IMMUTABLE
AS $$
    import re
    regexp = re.compile("^([0-9]{6})[0-9]{5,6}([0-9]{4})")
 
    match = regexp.search(credit_card)
    if match != None:
        first = match.group(1)
        last = match.group(2)
    else:
        first = "000000"
        last = "0000"
    
    return "{}XXXXX{}".format(first, last)
$$ LANGUAGE plpythonu;

--Create a masking policy that partially redacts credit card numbers if the is_fraud value for that row is TRUE,
--and otherwise blanks out the credit card number completely.
CREATE MASKING POLICY card_number_conditional_mask
    WITH (fraudulent BOOLEAN, pan varchar(16)) 
    USING (CASE WHEN fraudulent THEN REDACT_CREDIT_CARD(pan)
                ELSE Null
           END);

--Attach the masking policy to the credit_cards/analyst table/role pair. 
ATTACH MASKING POLICY card_number_conditional_mask ON credit_cards (credit_card_number)
 USING (is_fraud, credit_card_number)
 TO ROLE analyst PRIORITY 100;