CREATE TYPE statement specifies the name of the type and its attributes, methods, and other properties.
TYPE statement creates or replaces the specification of one of these:
Abstract Data Type (ADT)
Standalone varying array (varray) type
Standalone nested table type
Incomplete object type
An incomplete type is a type created by a forward type definition. It is called incomplete because it has a name but no attributes or methods. It can be referenced by other types, allowing you to define types that refer to each other. However, you must fully specify the type before you can use it to create a table or an object column or a column of a nested table type.
BODY statement contains the code for the methods that implement the type.
If you create a type whose specification declares only attributes but no methods, then you need not specify a type body.
A standalone collection type that you create with the
TYPEstatement differs from a collection type that you define with the keyword
TYPEin a PL/SQL block or package. For information about the latter, see "Collection Variable Declaration".
TYPEstatement, you can create nested table and
VARRAYtypes, but not associative arrays. In a PL/SQL block or package, you can define all three collection types.
To create a type in your schema, you must have the
TYPE system privilege. To create a type in another user's schema, you must have the
TYPE system privilege. You can acquire these privileges explicitly or be granted them through a role.
To create a subtype, you must have the
TYPE system privilege or the
UNDER object privilege on the supertype.
The owner of the type must be explicitly granted the
EXECUTE object privilege to access all other types referenced in the definition of the type, or the type owner must be granted the
TYPE system privilege. The owner cannot obtain these privileges through roles.
If the type owner intends to grant other users access to the type, then the owner must be granted the
EXECUTE object privilege on the referenced types with the
OPTION or the
TYPE system privilege with the
OPTION. Otherwise, the type owner has insufficient privileges to grant access on the type to other users.
Re-creates the type if it exists, and recompiles it.
Users who were granted privileges on the type before it was redefined can still access the type without being regranted the privileges.
If any function-based indexes depend on the type, then the database marks the indexes
[ EDITIONABLE | NONEDITIONABLE ]
Specifies whether the type is an editioned or noneditioned object if editioning is enabled for the schema object type
EDITIONABLE. For information about editioned and noneditioned objects, see Oracle Database Development Guide.
Name of the schema containing the type. Default: your schema.
Name of an ADT, a nested table type, or a
If creating the type results in compilation errors, then the database returns an error. You can see the associated compiler error messages with the SQL*Plus command
The database implicitly defines a constructor method for each user-defined type that you create. A constructor is a system-supplied procedure that is used in SQL statements or in PL/SQL code to construct an instance of the type value. The name of the constructor method is the name of the user-defined type. You can also create a user-defined constructor using the
The parameters of the ADT constructor method are the data attributes of the ADT. They occur in the same order as the attribute definition order for the ADT. The parameters of a nested table or varray constructor are the elements of the nested table or the varray.
type_name exists and has type dependents, but not table dependents,
FORCE forces the statement to replace the type. (If
type_name has table dependents, the statement fails with or without
t1 has type dependent
t2, and type
t2 has table dependents, then type
t1 also has table dependents.
Establishes type equivalence of identical objects in multiple databases. See Oracle Database Object-Relational Developer's Guide for information about this clause.
Creates a schema-level ADT. Such ADTs are sometimes called root ADTs.
IS | AS
AS is required when creating an ADT.
Creates a subtype of an existing type.
The existing supertype must be an ADT. The subtype you create in this statement inherits the properties of its supertype. It must either override some of those properties or add properties to distinguish it from the supertype.
Name of an ADT attribute. An ADT attribute is a data item with a name and a type specifier that forms the structure of the ADT. You must specify at least one attribute for each ADT. The name must be unique in the ADT, but can be used in other ADTs.
If you are creating a subtype, then the attribute name cannot be the same as any attribute or method name declared in the supertype chain.
The data type of an ADT attribute. This data type must be stored in the database; that is, either a predefined data type or a user-defined standalone collection type.
Restrictions on datatype
You cannot impose the
NULLconstraint on an attribute.
You cannot specify attributes of type
You cannot specify a data type of
UROWIDfor an ADT.
If you specify an object of type
REF, then the target object must have an object identifier.
If you are creating a collection type for use as a nested table or varray column of a table, then you cannot specify attributes of type
Creates an ADT. The variables that form the data structure are called attributes. The member subprograms that define the behavior of the ADT are called methods.
OBJECT is required.
[NOT] FINAL, [NOT] INSTANTIABLE , [NOT] PERSISTABLE
At the schema level of the syntax, these clauses specify the inheritance attributes of the type.
Use the [
FINAL clause to indicate whether any further subtypes can be created for this type:
FINALif no further subtypes can be created for this type.
FINALif further subtypes can be created under this type.
Use the [
INSTANTIABLE clause to indicate whether any object instances of this type can be constructed:
INSTANTIABLEif object instances of this type can be constructed.
INSTANTIABLEif no default or user-defined constructor exists for this ADT. You must specify these keywords for any type with noninstantiable methods and for any type that has no attributes, either inherited or specified in this statement.
PERSISTABLE clause to indicate whether or not instances of the object type are persistable.
PERSISTABLE types can be stored in a table.
(Default) You can specify
PERSISTABLEif all the object type attributes are persistable. Creating a persistable object type with non-persistable attributes is not allowed.
You can specify
PERSISTABLEif the object type attributes are persistable or non-persistable.
You cannot specify the
[NOT] PERSISTABLE clause in a subtype definition. The persistance property of a subtype is inherited from its supertype.
Creates the type as an ordered set of elements, each of which has the same data type.
Restrictions on varray_type_spec
You can create a
VARRAY type of
XMLType or of a LOB type for procedural purposes, for example, in PL/SQL or in view queries. However, database storage of such a varray is not supported, so you cannot create an object table or an column of such a
( datatype [NOT NULL] )
The parentheses before and after the
NOT NULL] clause are required when
PERSISTABLE is specified. The parentheses are optional if
PERSISTABLE is not specified.
PERSISTABLE clause to indicate whether or not instances of the collection type (
VARRAY or nested table) are persistable.
(Default) A collection can be
PERSISTABLEonly if the collection element type is persistable. Creating a persistable collection type with non-persistable element type is not allowed.
PERSISTABLEif any element type of the collection is not persistable. You can specify
PERSISTABLEfor any collection, whether the element type is persistable or not.
Creates a named nested table of type
[NOT] PERSISTABLESame as for
VARRAY, see " [NOT] PERSISTABLE"
Example 14-23 ADT Examples
This example shows how the sample type
customer_typ was created for the sample Order Entry (
oe) schema. A hypothetical name is given to the table so that you can duplicate this example in your test database:
CREATE TYPE customer_typ_demo AS OBJECT ( customer_id NUMBER(6) , cust_first_name VARCHAR2(20) , cust_last_name VARCHAR2(20) , cust_address CUST_ADDRESS_TYP , phone_numbers PHONE_LIST_TYP , nls_language VARCHAR2(3) , nls_territory VARCHAR2(30) , credit_limit NUMBER(9,2) , cust_email VARCHAR2(30) , cust_orders ORDER_LIST_TYP ) ;
In this example, the
data_typ1 ADT is created with one member function
prod, which is implemented in the
CREATE TYPE data_typ1 AS OBJECT ( year NUMBER, MEMBER FUNCTION prod(invent NUMBER) RETURN NUMBER ); / CREATE TYPE BODY data_typ1 IS MEMBER FUNCTION prod (invent NUMBER) RETURN NUMBER IS BEGIN RETURN (year + invent); END; END;
Example 14-24 Creating a Subtype
This statement shows how the subtype
corporate_customer_typ in the sample
oe schema was created.
It is based on the
customer_typ supertype created in the preceding example and adds the
account_mgr_id attribute. A hypothetical name is given to the table so that you can duplicate this example in your test database:
CREATE TYPE corporate_customer_typ_demo UNDER customer_typ ( account_mgr_id NUMBER(6) );
Example 14-25 Creating a Type Hierarchy
These statements create a type hierarchy.
employee_t inherits the
ssn attributes from type
person_t and in addition has
salary attributes. Type
part_time_emp_t inherits all of the attributes from
employee_t and, through
employee_t, those of
person_t and in addition has a
num_hrs attribute. Type
part_time_emp_t is final by default, so no further subtypes can be created under it.
CREATE TYPE person_t AS OBJECT (name VARCHAR2(100), ssn NUMBER) NOT FINAL; CREATE TYPE employee_t UNDER person_t (department_id NUMBER, salary NUMBER) NOT FINAL; CREATE TYPE part_time_emp_t UNDER employee_t (num_hrs NUMBER);
You can use type hierarchies to create substitutable tables and tables with substitutable columns.
Example 14-26 Creating a Varray Type
This statement shows how the
VARRAY type with five elements in the sample
oe schema was created.
A hypothetical name is given to the table so that you can duplicate this example in your test database:
CREATE TYPE phone_list_typ_demo AS VARRAY(5) OF VARCHAR2(25);
Example 14-27 Creating a Nested Table Type
This example from the sample schema
pm creates the table type
textdoc_tab of type
CREATE TYPE textdoc_typ AS OBJECT ( document_typ VARCHAR2(32) , formatted_doc BLOB ) ; CREATE TYPE textdoc_tab AS TABLE OF textdoc_typ;
Example 14-28 Creating a Nested Table Type Containing a Varray
This example of multilevel collections is a variation of the sample table
In this example, the
cust_address object column becomes a nested table column with the
phone_list_typ varray column embedded in it. The phone_list_typ_demo type was created in "Example 14-26".
CREATE TYPE cust_address_typ2 AS OBJECT ( street_address VARCHAR2(40) , postal_code VARCHAR2(10) , city VARCHAR2(30) , state_province VARCHAR2(10) , country_id CHAR(2) , phone phone_list_typ_demo ); CREATE TYPE cust_nt_address_typ AS TABLE OF cust_address_typ2;
Example 14-29 Constructor Example
This example invokes the system-defined constructor to construct the
demo_typ object and insert it into the
CREATE TYPE demo_typ1 AS OBJECT (a1 NUMBER, a2 NUMBER); CREATE TABLE demo_tab1 (b1 NUMBER, b2 demo_typ1); INSERT INTO demo_tab1 VALUES (1, demo_typ1(2,3));
Example 14-30 Creating a Member Method
This example invokes method constructor
First the type is created:
CREATE TYPE demo_typ2 AS OBJECT (a1 NUMBER, MEMBER FUNCTION get_square RETURN NUMBER);
Next a table is created with an ADT column and some data is inserted into the table:
CREATE TABLE demo_tab2(col demo_typ2); INSERT INTO demo_tab2 VALUES (demo_typ2(2));
The type body is created to define the member function, and the member method is invoked:
CREATE TYPE BODY demo_typ2 IS MEMBER FUNCTION get_square RETURN NUMBER IS x NUMBER; BEGIN SELECT c.col.a1*c.col.a1 INTO x FROM demo_tab2 c; RETURN (x); END; END; SELECT t.col.get_square() FROM demo_tab2 t; T.COL.GET_SQUARE() ------------------ 4
Unlike function invocations, method invocations require parentheses, even when the methods do not have additional arguments.
Example 14-31 Creating a Static Method
This example changes the definition of the
employee_t type to associate it with the
The example first creates an ADT
department_t and then an ADT
employee_t containing an attribute of type
CREATE OR REPLACE TYPE department_t AS OBJECT ( deptno number(10), dname CHAR(30)); CREATE OR REPLACE TYPE employee_t AS OBJECT( empid RAW(16), ename CHAR(31), dept REF department_t, STATIC function construct_emp (name VARCHAR2, dept REF department_t) RETURN employee_t );
This statement requires this type body statement.
CREATE OR REPLACE TYPE BODY employee_t IS STATIC FUNCTION construct_emp (name varchar2, dept REF department_t) RETURN employee_t IS BEGIN return employee_t(SYS_GUID(),name,dept); END; END;
Next create an object table and insert into the table:
CREATE TABLE emptab OF employee_t; INSERT INTO emptab VALUES (employee_t.construct_emp('John Smith', NULL));
In this chapter:
In other chapters:
Collection Types for information about user-defined standalone collection types
- PL/SQL Data Types
In other books:
Oracle Database Object-Relational Developer's Guide for more information about objects, incomplete types, varrays, and nested tables
Oracle Database Object-Relational Developer's Guide for more information about constructors