|Oracle9i SQL Reference
Release 2 (9.2)
Part Number A96540-01
SQL Statements: ALTER TRIGGER to COMMIT , 3 of 11
TYPE statement to add or drop member attributes or methods. You can change the existing properties (
INSTANTIABLE) of an object type, and you can modify the scalar attributes of the type.
You can also use this statement to recompile the specification or body of the type or to change the specification of an object type by adding new object member subprogram specifications.
The object type must be in your own schema and you must have
TYPE system privilege, or you must have
TYPE system privileges.
Specify the schema that contains the type. If you omit
schema, then Oracle assumes the type is in your current schema.
Specify the name of an object type, a nested table type, or a rowid type.
COMPILE to compile the object type specification and body. This is the default if neither
BODY is specified.
During recompilation, Oracle drops all persistent compiler switch settings, retrieves them again from the session, and stores them at the end of compilation. To avoid this process, specify the
If recompiling the type results in compilation errors, then Oracle returns an error and the type remains invalid. You can see the associated compiler error messages with the SQL*Plus command
DEBUG to instruct the PL/SQL compiler to generate and store the code for use by the PL/SQL debugger.
SPECIFICATION to compile only the object type specification.
BODY to compile only the object type body.
SETTINGS to prevent Oracle from dropping and reacquiring compiler switch settings. With this clause, Oracle preserves the existing settings and uses them for the recompilation.
If you specify both
SETTINGS, Oracle sets the persistently stored value of the
PLSQL_COMPILER_FLAGS parameter to
DEBUG. No other compiler switch values are changed.
PL/SQL User's Guide and Reference and Oracle9i Application Developer's Guide - Fundamentals for more information on the interaction of the
OBJECT clause lets you add new member subprogram specifications. This clause is valid only for object types, not for nested table or varray types.
Specify an object attribute name. Attributes are data items with a name and a type specifier that form the structure of the object.
Specify the elements of the redefined object.
As part of the
inheritance_clauses let you specify the relationship between super- and subtypes.
This clause is valid only for
MEMBER methods. Specify
OVERRIDING to indicate that this method overrides a
MEMBER method defined in the supertype. This keyword is required if the method redefines a supertype method.
OVERRIDING is the default.
OVERRIDING clause is not valid for a
STATIC method or for a SQLJ object type.
FINAL to indicate that this method cannot be overridden by any subtype of this type. The default is
INSTANTIABLE if the type does not provide an implementation for this method. By default all methods are
INSTANTIABLE: If you specify
INSTANTIABLE, you cannot specify
STATIC clauses let you specify a function or procedure subprogram associated with the object type which is referenced as an attribute.
You must specify a corresponding method body in the object type body for each procedure or function specification.
Enter the specification of a procedure subprogram.
Enter the specification of a function subprogram.
pragma_clause is a complier directive that denies member functions read/write access to database tables, packaged variables, or both, and thereby helps to avoid side effects.
Oracle Corporation recommends that you avoid using this clause unless you must do so for backward compatibility of your applications. This clause has been deprecated, because beginning with Oracle9i, Oracle runs purity checks at run time.
Restriction on the pragma_clause: The
pragma_clause is not valid when dropping a method.
You can declare either a
MAP method or an
ORDER method, but not both. However, a subtype can override a
MAP method if the supertype defines a
MAP method. If you declare either method, then you can compare object instances in SQL.
If you do not declare either method, then you can compare object instances only for equality or inequality. Instances of the same type definition are equal only if each pair of their corresponding attributes is equal. No comparison method needs to be specified to determine the equality of two object types.
"Object Values"for more information about object value comparisons
MAP, specify a member function (
MAPmethod) 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. Oracle uses the ordering for comparison conditions and
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 function can have no arguments other than the implicit
A subtype cannot define a new
MAP method. However, it can override an inherited
ORDER, specify a member function (
ORDERmethod) that takes an instance of an object as an explicit argument and the implicit
SELFargument and returns either a negative, zero, or positive integer. The negative, zero, or positive indicates that the implicit
SELFargument 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 object type definition are compared in an
BY clause, the
ORDER method function is invoked.
An object specification can contain only one
ORDER method, which must be a function having the return type
A subtype cannot define an
ORDER method, nor can it override an inherited
invoker_rights_clause lets you specify whether the member functions and procedures of the object type execute with the privileges and in the schema of the user who owns the object type or with the privileges and in the schema of
CURRENT_USER. This specification applies to the corresponding type body as well.
This clause also determines how Oracle resolves external names in queries, DML operations, and dynamic SQL statements in the member functions and procedures of the type.
Restriction on the invoker_rights_clause: You can specify this clause only for an object type, not for a nested table or varray type.
CURRENT_USER if you want the member functions and procedures of the object type to execute with the privileges of
CURRENT_USER. This clause creates an invoker-rights type.
This clause also specifies that external names in queries, DML operations, and dynamic SQL statements resolve in the schema of
CURRENT_USER. External names in all other statements resolve in the schema in which the type resides.
You must specify this clause to maintain invoker-rights status for the type if you created it with this status. Otherwise the status will revert to definer rights.
DEFINER if you want the member functions and procedures of the object type to execute with the privileges of the owner of the schema in which the functions and procedures reside, and that external names resolve in the schema where the member functions and procedures reside. This is the default.
alter_method_spec lets you add a method to or drop a method from
type. Oracle disables any function-based indexes that depend on the type.
TYPE statement you can add or drop multiple methods, but you can reference each method only once.
When you add a method, its name must not conflict with any existing attributes in its type hierarchy.
When you drop a method, Oracle removes the method from the target type.
Restriction on DROP: You cannot drop from a subtype a method inherited from its supertype. Instead you must drop the method from the supertype.
STATIC clauses let you add a procedure subprogram to or drop it from the object type.
Restriction on subprogram_clauses: You cannot define a
STATIC method on a subtype that redefines a
MEMBER method in its supertype, or vice versa.
the description of the
If you declare either a
ORDER method, then you can compare object instances in SQL.
Restriction on map_order_function_spec: You cannot add an
ORDER method to a subtype.
the description of
alter_attribute_definition clause lets you add, drop, or modify an attribute of an object type. In one
TYPE statement, you can add, drop, or modify multiple member attributes or methods, but you can reference each attribute or method only once.
The name of the new attribute must not conflict with existing attributes or methods in the type hierarchy. Oracle adds the new attribute to the end of the locally defined attribute list.
If you add the attribute to a supertype, then it is inherited by all of its subtypes. In subtypes, inherited attributes always precede declared attributes. Therefore, you may need to update the mappings of the implicitly altered subtypes after adding an attribute to a supertype.
When you drop an attribute from a type, Oracle drops the column corresponding to the dropped attribute as well as any indexes, statistics, and constraints referencing the dropped attribute.
You need not specify the datatype of the attribute you are dropping.
Restrictions on dropping attributes:
This clause lets you modify the datatype of an existing scalar attribute. For example, you can increase the length of a
RAW attribute, or you can increase the precision or scale of a numeric attribute.
Restriction on modifying an attribute: You cannot expand the size of an attribute referenced in a function-based index, domain index, or cluster key.
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.
If you change the property between
FINAL, then you must specify the
CASCADE clause of the
dependent_handling_clause to convert data in dependent columns and tables. You cannot defer data conversion with
FINAL, then you must specify
DATAif you want to create new substitutable tables and columns of that type, but you are not concerned about the substitutability of the existing dependent tables and columns. Oracle marks all existing dependent columns and tables
LEVELS, so you cannot insert the new subtype instances of the altered type into these existing columns and tables.
SUBSTITUTABLEif you want to create new substitutable tables and columns of the type and also store new subtype instances of the altered type in existing dependent tables and columns. Oracle marks all existing dependent columns and tables
LEVELSexcept those that are explicitly marked
Restriction on FINAL: You cannot change a user-defined type from
FINAL if the type has any subtypes.
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 constructor (default or user-defined) exists for this object type. 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).
Restriction on NOT INSTANTIABLE: You cannot change a user-defined type from
INSTANTIABLE if the type has any table dependents.
dependent_handling_clause lets you instruct Oracle how to handle objects that are dependent on the modified type. If this clause is not specified, then the
TYPE statement will abort if the target type has any dependent type or table.
INVALIDATE to invalidate all dependent objects without any checking mechanism.
Because Oracle does not validate the type change, you should use this clause with caution. For example, if you drop an attribute that is a partitioning or cluster key, then you will be unable to write to the table.
CASCADE clause if you want to propagate the type change to dependent types and tables. Oracle aborts the statement if any errors are found in the dependent types or tables unless you also specify
DATA to convert data stored in all user-defined columns to the most recent version of the column's type. This is the default.
You must specify this clause if your column data is in Oracle8 release 8.0 image format. This clause is also required if the type property is being changed between
When you specify
DATA, all of the tablespaces containing the table's data must be in read/write mode.
If you specify
DATA, then Oracle upgrades the metadata of the column to reflect the changes to the type, but does not scan the dependent column and update the data as part of this
TYPE statement. However, the dependent column data remains accessible and the results of subsequent queries of the data will reflect the type modifications.
Oracle9i Application Developer's Guide - Object-Relational Features for more information on the implications of not including table data when modifying type attribute
FORCE if you want Oracle to ignore the errors from dependent tables and indexes and log all errors in the specified exception table. The exception table must already have been created by executing the
The following example uses the
data_typ object type, which was created in "Object Type Examples". A method is added to
data_typ and its type body is modified to correspond. The date formats are consistent with the
order_date column of the
oe.orders sample table:
ALTER TYPE data_typ ADD MEMBER FUNCTION qtr(der_qtr DATE) RETURN CHAR CASCADE; CREATE OR REPLACE TYPE BODY data_typ IS MEMBER FUNCTION prod (invent NUMBER) RETURN NUMBER IS BEGIN RETURN (year + invent); END; MEMBER FUNCTION qtr(der_qtr DATE) RETURN CHAR IS BEGIN IF (der_qtr < TO_DATE('01-APR', 'DD-MON')) THEN RETURN 'FIRST'; ELSIF (der_qtr < TO_DATE('01-JUL', 'DD-MON')) THEN RETURN 'SECOND'; ELSIF (der_qtr < TO_DATE('01-OCT', 'DD-MON')) THEN RETURN 'THIRD'; ELSE RETURN 'FOURTH'; END IF; END; END; /
The following example adds the
phone_list_typ varray from the sample
oe schema to the
customer_address_typ object column of the
ALTER TYPE cust_address_typ ADD ATTTRIBUTE (phone phone_list_typ) CASCADE;
The following example recompiles type
The following example compiles the type specification of
CREATE TYPE link1 AS OBJECT (a NUMBER); / CREATE TYPE link2 AS OBJECT (a NUMBER, b link1, MEMBER FUNCTION p(c1 NUMBER) RETURN NUMBER); / CREATE TYPE BODY link2 AS MEMBER FUNCTION p(c1 NUMBER) RETURN NUMBER IS BEGIN dbms_output.put_line(c1); RETURN c1; END; END; /
In the following example, both the specification and body of
link2 are invalidated.
ALTER TYPE link1 ADD ATTRIBUTE (b NUMBER) INVALIDATE;
You must recompile the type by recompiling the specification and body in separate statements:
ALTER TYPE link2 COMPILE SPECIFICATION; ALTER TYPE link2 COMPILE BODY;
Alternatively, you can compile both specification and body at the same time:
ALTER TYPE link2 COMPILE;