REFTOHEX(<expr>);
 
CREATE TABLE warehouse_table OF warehouse_typ
   (PRIMARY KEY (warehouse_id));
 
CREATE TABLE location_table
   (location_number NUMBER, building REF warehouse_typ 
   SCOPE IS warehouse_table);
 
INSERT INTO warehouse_table VALUES (1, 'Downtown', 99);
 
INSERT INTO location_table SELECT 10, REF(w) FROM warehouse_table w;
 
SELECT REFTOHEX(building) FROM location_table;
 
REFTOHEX(BUILDING)
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0000220208859B5E9255C31760E034080020825436859B5E9255C21760E034080020825436