Reference Guide
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Dynamic Data Masking
Creating a Masking Policy
a masking policy must be defined for the database to activate the masking feature when using sql proxies navigate to policy > policy click the add n ext to the policy key title select the sql masking policy inside of the policy key type in the opened pop up enter the masking name, description, database name, schema, table, column or column type, and masking method (defined in the masking method tab) click save