YashanDB TREAT 函数

CREATE OR REPLACE TYPE udt_object_sp FORCE IS OBJECT (    branch_no CHAR(4),    branch_name VARCHAR2(200)) NOT FINAL;/
CREATE OR REPLACE TYPE udt_object_sub FORCE UNDER udt_object_sp (    area_no CHAR(2),    address VARCHAR2(200)) NOT FINAL;/
DECLARE    obj1 udt_object_sub := udt_object_sub('0101','Beijing','01','North Street');    obj2 udt_object_sp;BEGIN    obj2 := TREAT (obj1 AS udt_object_sp);    DBMS_OUTPUT.PUT_LINE(obj2.branch_name);END;/
DECLARE    obj1 udt_object_sp := udt_object_sub('0101','Beijing','01','North Street');    obj2 udt_object_sub;BEGIN    obj2 := TREAT (obj1 AS udt_object_sub);    DBMS_OUTPUT.PUT_LINE(obj2.branch_name);END;/