Use a named row type within another row type

You can use a named row type as the data type of a field within another row type. A nested row type is a row type that contains another row type. You can nest any row type within any other row type. No practical limit exists on how deeply you can nest row types. However, to perform inserts or updates on deeply nested row types requires careful use of the syntax.

For named row types, the order in which you create the row types is important because a named row type must exist before you can use it to define a column or a field within another row type. In the following example, the first statement creates the address_t type, which is used in the second statement to define the type of the address field of the employee_t type: 
CREATE ROW TYPE address_t
(
   street  VARCHAR (20),
   city    VARCHAR(20),
   state   CHAR(2),
   zip     VARCHAR(9)
);

CREATE ROW TYPE employee_t
(
   name     VARCHAR(30) NOT NULL,
   address  address_t,
   salary   INTEGER
);
Important: You cannot use a row type recursively. If type_t is a row type, then you cannot use type_t as the data type of a field contained in type_t.