14.13 CREATE TYPE Statement
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 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.
See "call_spec ::=".
See "call_spec ::=".
See "call_spec ::=".
See "function_spec ::=".
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 the type as an ordered set of elements, each of which has the same data type.
Restrictions on varray_type_def
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
Creates a named nested table 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 are required when creating an ADT.
Creates a schema-level ADT. Such ADTs are sometimes called root ADTs.
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.
"Example 14-24" and "Example 14-25"
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. For information about predefined data types, see PL/SQL Data Types. For information about user-defined standalone collection types, see "Collection Types".
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
Specifies each attribute of the ADT.
[NOT] FINAL, [NOT] INSTANTIABLE
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.
Associates a procedure subprogram with the ADT.
A function or procedure subprogram associated with the ADT that is referenced as an attribute. Typically, you invoke
MEMBER methods in a selfish style, such as
(). This class of method has an implicit first argument referenced as
SELF in the method body, which represents the object on which the method was invoked.
A function or procedure subprogram associated with the ADT. Unlike
STATIC methods do not have any implicit parameters. You cannot reference
SELF in their body. They are typically invoked as
Restrictions on STATIC
You cannot map a
MEMBERmethod in a Java class to a
STATICmethod in a SQLJ object type.
STATICmethods, you must specify a corresponding method body in the type body for each procedure or function specification.
Deprecated clause, described in "RESTRICT_REFERENCES Pragma".
Specify the relationship between supertypes and subtypes.
Specifies that this method overrides a
MEMBER method defined in the supertype. This keyword is required if the method redefines a supertype method. Default:
Specifies that this method cannot be overridden by any subtype of this type. Default:
Specifies that the type does not provide an implementation for this method. Default: all methods are
Restriction on NOT INSTANTIABLE
If you specify
INSTANTIABLE, then you cannot specify
procedure_spec or function_spec
Specifies the parameters and data types of the procedure or function. If this subprogram does not include the declaration of the procedure or function, then you must issue a corresponding
Restriction on procedure_spec or function_spec
If you are creating a subtype, then the name of the procedure or function cannot be the same as the name of any attribute, whether inherited or not, declared in the supertype chain.
The first form of the return_clause is valid only for a function. The syntax shown is an abbreviated form.
"Collection Method Invocation" for information about method invocation and methods
"CREATE PROCEDURE Statement" and "CREATE FUNCTION Statement" for the full syntax with all possible clauses
Creates a user-defined constructor, which is a function that returns an initialized instance of an ADT. You can declare multiple constructors for a single ADT, if the parameters of each constructor differ in number, order, or data type.
User-defined constructor functions are always
INSTANTIABLE, so these keywords are optional.
The parameter-passing mode of user-defined constructors is always
OUT. Therefore you need not specify this clause unless you want to do so for clarity.
RESULTspecifies that the runtime type of the value returned by the constructor is runtime type of the
Oracle Database Object-Relational Developer's Guide for more information about and examples of user-defined constructors and "Example 14-29"
You can define either one
MAP method or one
ORDER method in a type specification, regardless of how many
STATIC methods you define. If you declare either method, then you can compare object instances in SQL.
You cannot define either
ORDER methods for subtypes. However, a subtype can override a
MAP method if the supertype defines a nonfinal
MAP method. A subtype cannot override an
ORDER method at all.
You can specify either
ORDER when mapping a Java class to a SQL type. However, the
ORDER methods must map to
MEMBER functions in the Java class.
If neither a
MAP nor an
ORDER method is specified, then only comparisons for equality or inequality can be performed. Therefore object instances cannot be ordered. Instances of the same type definition are equal only if each pair of their corresponding attributes is equal. No comparison method must be specified to determine the equality of two ADTs.
MAP if you are performing extensive sorting or hash join operations on object instances.
MAP is applied once to map the objects to scalar values, and then the database uses the scalars during sorting and merging. A
MAP method is more efficient than an
ORDER method, which must invoke the method for each object comparison. You must use a
MAP method for hash joins. You cannot use an
ORDER method because the hash mechanism hashes on the object value.
Oracle Database Object-Relational Developer's Guide for more information about object value comparisons
MAP member function that returns the relative position of a given instance in the ordering of all instances of the object. A
MAP method is called implicitly and induces an ordering of object instances by mapping them to values of a predefined scalar type. PL/SQL uses the ordering to evaluate Boolean expressions and to perform comparisons.
If the argument to the
MAP method is null, then the
MAP method returns null and the method is not invoked.
An object specification can contain only one
MAP method, which must be a function. The result type must be a predefined SQL scalar type, and the
MAP method can have no arguments other than the implicit
type_name is to be referenced in queries containing sorts (through an
UNION clause) or containing joins, and you want those queries to be parallelized, then you must specify a
MAP member function.
A subtype cannot define a new
MAP method, but it can override an inherited
ORDER member function that takes an instance of an object as an explicit argument and the implicit
SELF argument and returns either a negative, zero, or positive integer. The negative, positive, or zero indicates that the implicit
SELF argument is less than, equal to, or greater than the explicit argument.
If either argument to the
ORDER method is null, then the
ORDER method returns null and the method is not invoked.
When instances of the same ADT definition are compared in an
BY clause, the
map_order_function_spec is invoked.
An object specification can contain only one
ORDER method, which must be a function having the return type
A subtype can neither define nor override an
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 Subtype Example
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 Type Hierarchy Example
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 Varray Type Example
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 Nested Table Type Example
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 Nested Table Type Containing a Varray Example
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 type was created in "CREATE TYPE Statement".
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));
Oracle Database Object-Relational Developer's Guide for more information about constructors
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:
Oracle Database Object-Relational Developer's Guide for more information about objects, incomplete types, varrays, and nested tables