You can redact columns of different data types, using different redaction types and named policy expressions, for one table or view.

1. Connect to the PDB as a user who has the EXECUTE privilege on the DBMS_REDACT PL/SQL package and the ADMINISTER REDACTION POLICY system or schema privilege.
2. Create the policy for the first column that you want to redact by using DBMS_REDACT.ADD_POLICY.
3. Use the DBMS_REDACT.ALTER_POLICY procedure to add the next column to the policy.
   As necessary, set the action, column_name, function_type, and function_parameters (or the parameters that begin with regexp_) parameters to define the redaction for the new column, but do not change the object_schema, object_name, policy_name, or expression parameters. These parameters remain unchanged for newly redacted columns.
4. Create named policy expressions and apply them to the redacted column.
   If a named policy expression is not applied to the column, the default policy expression from DBMS_REDACT.ADD_POLICY will apply.

The DBMS_REDACT.ALTER_POLICY procedure can redact multiple columns.

Example 3-12 shows how to add a column to an existing Data Redaction policy. In this example, the action parameter specifies that a new column must be added, using DBMS_REDACT.ADD_COLUMN. The name of the new column, card_num, is set by the column_name parameter.

BEGIN
 DBMS_REDACT.ALTER_POLICY(
  object_schema       => 'mavis', 
  object_name         => 'cust_info', 
  policy_name         => 'redact_cust_user_ids', 
  action              => DBMS_REDACT.ADD_COLUMN,
  column_name         => 'card_num',
  function_type       => DBMS_REDACT.FULL);
END;
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