Tài liệu Oracle PL/SQL by Example- P12 pptx

CONSTRUCTOR FUNCTION zipcode_obj_typeSELF IN OUT NOCOPY ZIPCODE_OBJ_TYPE, zip VARCHAR2RETURN SELF AS RESULT, CONSTRUCTOR FUNCTION zipcode_obj_type SELF IN OUT NOCOPY ZIPCODE_OBJ_TYPE, zi

Next, take a closer look at the second SELECT INTO statement This statement uses CAST and TABLE functions, which essentially enable you to query a nested table of objects as if it were a regular table.

When run, this example produces the following output:

23.1.1 Use Object Types

In this exercise, you continue exploring object types

Complete the following tasks:

A) Create object type ENROLLMENT_OBJ_TYPE, which has the following attributes:

ATTRIBUTE NAME DATA TYPE PRECISION

B) The following script uses the newly created object type Execute it and explain the output

C) Modify the script created in the preceding exercise (ch23_2a.sql) so that it does not produce anORA-06530 error.

ANSWER:The script should look similar to the following Changes are shown in bold

D) Modify this script (ch23_2b.sql) so that all object attributes are populated with corresponding

values selected from the appropriate tables

ANSWER:The script should look similar to one of the following scripts Changes are shown

in bold

The first version of the script employs the SELECT INTO statement along with the constructor toinitialize other attributes as well Note that the SELECT INTO statement specifies WHERE criteria forthe SECTION_NO in addition to the criteria for the STUDENT_ID and COURSE_NO This ensuresthat the SELECT INTO statement does not cause an ORA-01422: exact fetch returnsmore than requested number of rowserror

c.course_no, se.section_no, e.enroll_date, e.final_grade)

INTO v_enrollment_obj

FROM student st, course c, section se, enrollment e WHERE st.student_id = e.student_id

AND c.course_no = se.course_no AND se.section_id = e.section_id AND st.student_id = 102

AND c.course_no = 25 AND se.section_no = 2;

END;

The SELECT statement in the preceding script can be modified according to the ANSI 1999 SQLstandard:

SELECT enrollment_obj_type(st.student_id, st.first_name,

st.last_name, c.course_no, se.section_no,e.enroll_date, e.final_grade)

INTO v_enrollment_objFROM enrollment eJOIN student st

ON e.student_id = st.student_idJOIN section se

ON e.section_id = se.section_idJOIN course c

ON se.course_no = c.course_noWHERE st.student_id = 102

AND c.course_no = 25AND se.section_no = 2;

The preceding SELECT statement uses the ON syntax to specify the join condition between fourtables This type of join becomes especially useful when the columns participating in the join donot have the same name

BY THE WAY

You will find detailed explanations and examples of the statements using the new ANSI 1999 SQLstandard in Appendix C and in the Oracle help Throughout this book we have tried to provide youwith examples illustrating both standards; however, our main focus has remained on PL/SQL featuresrather than SQL

The second version of the script uses a cursor FOR loop This approach eliminates the need foradditional criteria against the SECTION_NO

FOR REC IN (SELECT st.student_id, st.first_name, st.last_name,

c.course_no, se.section_no, e.enroll_date, e.final_grade

FROM student st, course c, section se, enrollment e WHERE st.student_id = e.student_id

AND c.course_no = se.course_no

AND se.section_id = e.section_id AND st.student_id = 102

AND c.course_no = 25) LOOP

v_enrollment_obj :=

enrollment_obj_type(rec.student_id, rec.first_name,

rec.last_name, rec.course_no, rec.section_no, rec.enroll_date, rec.final_grade);

END LOOP;

END;

E) Modify one of the scripts created in the previous exercises (use either ch23_2c.sql or ch23_2d.sql)

so that attribute values are displayed on the screen

ANSWER:The script should look similar to the following All changes are shown in bold

FOR REC IN (SELECT st.student_id, st.first_name, st.last_name,

c.course_no, se.section_no, e.enroll_date,e.final_grade

FROM student st, course c, section se, enrollment eWHERE st.student_id = e.student_id

AND c.course_no = se.course_noAND se.section_id = e.section_idAND st.student_id = 102

AND c.course_no = 25)LOOP

v_enrollment_obj :=

enrollment_obj_type(rec.student_id, rec.first_name,

rec.last_name, rec.course_no,rec.section_no, rec.enroll_date,rec.final_grade);

PL/SQL procedure successfully completed.

23.1.2 Use Object Types with Collections

In this exercise, you continue exploring how object types may be used with collections

Complete the following tasks:

A) Modify script ch23_2e.sql, created in the preceding exercise In the new version of the script,

populate an associative array of objects Use multiple student IDs for this exercise—102, 103,

FOR REC IN (SELECT st.student_id, st.first_name, st.last_name,

c.course_no, se.section_no, e.enroll_date,e.final_grade

FROM student st, course c, section se, enrollment eWHERE st.student_id = e.student_id

AND c.course_no = se.course_noAND se.section_id = e.section_idAND st.student_id in (102, 103, 104))

LOOPv_counter := v_counter + 1;

v_enrollment_tab(v_counter) :=

enrollment_obj_type(rec.student_id, rec.first_name,

rec.last_name, rec.course_no,rec.section_no, rec.enroll_date,rec.final_grade);

Take a closer look at how each row of the associative array is initialized:

v_enrollment_tab(v_counter) :=

enrollment_obj_type(rec.student_id, rec.first_name,

rec.last_name, rec.course_no,rec.section_no, rec.enroll_date,rec.final_grade);

A row is referenced by a subscript In this case it is a variable,v_counter Because each row

represents an object instance, it is initialized by referencing the default constructor method ciated with the corresponding object type

asso-When run, the script produces the following output:

-PL/SQL procedure successfully completed.

B) Modify the script so that the table of objects is populated using the BULK SELECT INTO statement

ANSWER:The script should look similar to the following Changes are shown in bold

c.course_no, se.section_no, e.enroll_date, e.final_grade)

BULK COLLECT INTO v_enrollment_tab FROM student st, course c, section se, enrollment e WHERE st.student_id = e.student_id

AND c.course_no = se.course_no AND se.section_id = e.section_id AND st.student_id in (102, 103, 104);

FOR i IN 1 v_enrollment_tab.COUNT LOOP

In this version of the script, the cursor FOR loop has been replaced by the BULK SELECT INTO

statement As a result, the cursor FOR loop is replaced by the numeric FOR loop to display data onthe screen These changes eliminate the need for the variable v_counter, which was used toreference individual rows of the associative array

When run, this version of the script produces output that is identical to the previous version

C) Modify the script so that data stored in the table of objects can be retrieved using the SELECT

INTO statement as well

ANSWER:As mentioned previously, for you to select data from a table of objects, the underlyingtable type must be either a nested table or a varray that is created and stored in the database

schema This is accomplished by the following statement:

CREATE OR REPLACE TYPE enroll_tab_type AS TABLE OF

c.course_no, se.section_no, e.enroll_date,e.final_grade)

BULK COLLECT INTO v_enrollment_tabFROM student st, course c, section se, enrollment eWHERE st.student_id = e.student_id

AND c.course_no = se.course_noAND se.section_id = e.section_idAND st.student_id in (102, 103, 104);

FOR rec IN (SELECT *

FROM TABLE(CAST(v_enrollment_tab AS enroll_tab_type)))

LOOP DBMS_OUTPUT.PUT_LINE ('student_id: '||rec.student_id);

DBMS_OUTPUT.PUT_LINE ('first_name: '||rec.first_name);

DBMS_OUTPUT.PUT_LINE ('last_name: '||rec.last_name);

DBMS_OUTPUT.PUT_LINE ('course_no: '||rec.course_no);

DBMS_OUTPUT.PUT_LINE ('section_no: '||rec.section_no);

DBMS_OUTPUT.PUT_LINE ('enroll_date: '||rec.enroll_date);

DBMS_OUTPUT.PUT_LINE ('final_grade: '||rec.final_grade);

L A B 2 3 2

Object Type Methods

L A B O B J E C T I V E

After completing this lab, you will be able to

Use object type methods

In Lab 23.1 you learned that object type methods are functions and procedures that specify actions that may be performed on the object type attributes and that they are defined in the object type specification You also have seen how to use default system-defined constructor methods The constructor is only one of the method types that PL/SQL supports Some other method types are member, static, map, and order The method type typically is determined by the actions that a particular method performs For example, constructor methods are used to initialize object instances, and map and order methods are used to compare and sort object instances.

Often object type methods use a built-in parameter called SELF This parameter represents a particular instance of the object type As such, it is available to the methods that are invoked on that object type instance You will see various examples of the SELF parameter in the following discussions.

CONSTRUCTOR METHODS

As discussed previously, a constructor method is a default method that is implicitly created by the system whenever a new object type is created It is a function that has the same name as its object type Its input parameters have the same names and datatypes as the object type attrib- utes and are listed in the same order as the object type attributes The constructor method returns a new instance of the object type In other words, it initializes a new object instance and assigns values to the object attributes Consider the following code fragments, which illustrate calls to the default constructor method for the zipcode_obj_type created earlier:

The first call to the constructor method returns a new instance, zip_obj1 , of zipcode_obj_ type with attributes initialized to non-null values The second call creates a new instance,

zip_obj2 , with NULL attribute values.

Note that both calls produce non-null instances of the zipcode_obj_type The difference is

in the values assigned to the individual attributes.

In the preceding examples, calls to the default constructor method use positional notation Recall that positional notation associates values with corresponding parameters by their position

in the header of the function, procedure, or, in this case, constructor Next, consider the call to the default constructor method that uses named notation Note that in this case, the order of parameters does not correspond to the order of the attributes in zipcode_obj_type Instead, they are referenced by their names:

FOR EXAMPLE

zip_obj3 := ZIPCODE_OBJ_TYPE(created_by => USER,

created_date => SYSDATE,modified_by => USER,modified_date => SYSDATE,zip =>'00914',city => 'Santurce',state => 'PR');

PL/SQL lets you create your own (user-defined) constructors User-defined constructors offer flexibility that default constructors lack For example, you may want to define a constructor on the zipcode_obj_type that initializes only some of the attributes of the newly created object instance In this case, the system initializes to NULL any attributes for which you do not specify values In addition, you can control the number and types of parameters that your constructor may require.

Consider the following example of the user-defined constructors for the zipcode_obj_type

FOR EXAMPLE

Note that before recreating zipcode_obj_type you must drop the nested table type

v_zip_tab_type , created in Lab 23.1, to prevent the following error message:

CREATE OR REPLACE TYPE zipcode_obj_type AS OBJECT

*

ERROR at line 1:

ORA-02303: cannot drop or replace a type with type or table

dependentsThe nested table type can be dropped as follows:

DROP TYPE v_zip_tab_type;

The object type can be recreated as shown here:

CREATE OR REPLACE TYPE zipcode_obj_type AS OBJECT

(zip VARCHAR2(5),

CONSTRUCTOR FUNCTION zipcode_obj_type

(SELF IN OUT NOCOPY ZIPCODE_OBJ_TYPE, zip VARCHAR2)RETURN SELF AS RESULT,

CONSTRUCTOR FUNCTION zipcode_obj_type

(SELF IN OUT NOCOPY ZIPCODE_OBJ_TYPE, zip VARCHAR2,city VARCHAR2, state VARCHAR2)

RETURN SELF AS RESULT);

/

CREATE OR REPLACE TYPE BODY zipcode_obj_type AS

CONSTRUCTOR FUNCTION zipcode_obj_type

(SELF IN OUT NOCOPY zipcode_obj_type, zip VARCHAR2)

RETURN SELF AS RESULT

IS

BEGIN

SELF.zip := zip;

SELECT city, state

INTO SELF.city, SELF.state

CONSTRUCTOR FUNCTION zipcode_obj_type

(SELF IN OUT NOCOPY ZIPCODE_OBJ_TYPE, zip VARCHAR2, city VARCHAR2,

This script overloads two constructor methods for zip_code_obj_type Overloading allows two methods or subprograms to use the same name as long as their parameters differ in either datatypes or their number In the preceding example, the first constructor method expects two parameters, and the second constructor method expects four parameters.

Both constructors use the default parameter SELF as an IN OUT parameter and as a return datatype in the RETURN clause As stated previously, SELF references a particular object type instance Note the use of the NOCOPY compiler hint This hint typically is used with OUT and

IN OUT parameters By default, OUT and IN OUT parameters are passed by value This means that the values of the parameters are copied before the subprogram or method is executed Then, during execution, temporary variables are used to hold values of the OUT parameters For the parameters that represent complex datatypes such as collections, records, and object type instances, the copying step can add significant processing overhead By adding a NOCOPY hint, you instruct the PL/SQL compiler to pass OUT and IN OUT parameters by reference and elim- inate the copying step.

Next, both constructor methods populate the city, state, and zip attributes Note how these attributes are referenced using the SELF parameter.

MEMBER METHODS

Member methods provide access to the object instance data As such, a member method should

be defined for each action that object type must perform For example, you may need to return city, state, and zip code values associated with an object instance to the calling application, as shown in the following example:

CONSTRUCTOR FUNCTION zipcode_obj_type

(SELF IN OUT NOCOPY ZIPCODE_OBJ_TYPE, zip VARCHAR2)RETURN SELF AS RESULT,

CONSTRUCTOR FUNCTION zipcode_obj_type

(SELF IN OUT NOCOPY ZIPCODE_OBJ_TYPE, zip VARCHAR2,city VARCHAR2, state VARCHAR2)

RETURN SELF AS RESULT,

MEMBER PROCEDURE get_zipcode_info

(out_zip OUT VARCHAR2, out_city OUT VARCHAR2,out_state OUT VARCHAR2)

/

CREATE OR REPLACE TYPE BODY zipcode_obj_type AS

CONSTRUCTOR FUNCTION zipcode_obj_type

(SELF IN OUT NOCOPY zipcode_obj_type, zip VARCHAR2)

RETURN SELF AS RESULT

IS

BEGIN

SELF.zip := zip;

SELECT city, state

INTO SELF.city, SELF.state

CONSTRUCTOR FUNCTION zipcode_obj_type

(SELF IN OUT NOCOPY ZIPCODE_OBJ_TYPE, zip VARCHAR2, city VARCHAR2,

MEMBER PROCEDURE get_zipcode_info

(out_zip OUT VARCHAR2, out_city OUT VARCHAR2, out_state OUT

VARCHAR2)IS

In this version of the script, you add a member procedure that returns values of zip code, city, and state associated with a particular instance of the zip_code_obj_type object type Note that the reference to the SELF parameter in this procedure is optional, and that the preceding assignment statements can be modified as follows:

CONSTRUCTOR FUNCTION zipcode_obj_type

(SELF IN OUT NOCOPY ZIPCODE_OBJ_TYPE, zip VARCHAR2)RETURN SELF AS RESULT,

CONSTRUCTOR FUNCTION zipcode_obj_type

(SELF IN OUT NOCOPY ZIPCODE_OBJ_TYPE, zip VARCHAR2,city VARCHAR2, state VARCHAR2)

RETURN SELF AS RESULT,

MEMBER PROCEDURE get_zipcode_info

(out_zip OUT VARCHAR2, out_city OUT VARCHAR2,out_state OUT VARCHAR2),

STATIC PROCEDURE display_zipcode_info

(in_zip_obj IN ZIPCODE_OBJ_TYPE));

/

CREATE OR REPLACE TYPE BODY zipcode_obj_type AS

CONSTRUCTOR FUNCTION zipcode_obj_type

(SELF IN OUT NOCOPY zipcode_obj_type, zip VARCHAR2)

RETURN SELF AS RESULT

IS

BEGIN

SELF.zip := zip;

SELECT city, state

INTO SELF.city, SELF.state

CONSTRUCTOR FUNCTION zipcode_obj_type

(SELF IN OUT NOCOPY ZIPCODE_OBJ_TYPE, zip VARCHAR2, city VARCHAR2,

MEMBER PROCEDURE get_zipcode_info

(out_zip OUT VARCHAR2, out_city OUT VARCHAR2, out_state OUT

VARCHAR2)IS

DBMS_OUTPUT.PUT_LINE ('Zip: ' ||in_zip_obj.zip);

DBMS_OUTPUT.PUT_LINE ('City: ' ||in_zip_obj.city);

DBMS_OUTPUT.PUT_LINE ('State: '||in_zip_obj.state);

END;

END;

/

In this version of the script, the static method displays zip code information on the screen It is important to note that even though this method references data associated with some object instance, this object instance is created elsewhere (such as in another PL/SQL script, function,

or procedure) and then passed into this method.

COMPARING OBJECTS

In PL/SQL, element datatypes such as VARCH AR2, NUMBER, and DATE have a predefined order that enables them to be compared to each other or sorted For example, the comparison operator > determines which variable contains a greater value, and the IF-THEN-ELSE state- ment evaluates to TRUE, FALSE, or NULL accordingly:

IF v_num1 > v_num2 THEN

Do somethingELSE

Do something elseEND IF;

However, an object type may contain multiple attributes of different datatypes and therefore does not have a predefined order Then, to be able to compare and sort object instances of the same object type, you must specify how these object instances should be compared and ordered You can do this using two types of optional member methods—map and order.

MAP METHODS

Map methods compare and order object instances, essentially by mapping an object instance

to an element (scalar) datatype such as DATE, NUMBER, or VARCHAR2 This mapping is used

to position an object instance on the axis (DATE, NUMBER, or VARCHAR2) used for the comparison.

A map method is a member function that does not accept any parameters and returns an element datatype, as demonstrated in the following example:

CONSTRUCTOR FUNCTION zipcode_obj_type

(SELF IN OUT NOCOPY ZIPCODE_OBJ_TYPE, zip VARCHAR2)RETURN SELF AS RESULT,

CONSTRUCTOR FUNCTION zipcode_obj_type

(SELF IN OUT NOCOPY ZIPCODE_OBJ_TYPE, zip VARCHAR2,

city VARCHAR2, state VARCHAR2)RETURN SELF AS RESULT,

MEMBER PROCEDURE get_zipcode_info

(out_zip OUT VARCHAR2, out_city OUT VARCHAR2,out_state OUT VARCHAR2),

STATIC PROCEDURE display_zipcode_info

(in_zip_obj IN ZIPCODE_OBJ_TYPE),MAP MEMBER FUNCTION zipcode RETURN VARCHAR2

);

/

CREATE OR REPLACE TYPE BODY zipcode_obj_type AS

CONSTRUCTOR FUNCTION zipcode_obj_type

(SELF IN OUT NOCOPY zipcode_obj_type, zip VARCHAR2)

RETURN SELF AS RESULT

IS

BEGIN

SELF.zip := zip;

SELECT city, state

INTO SELF.city, SELF.state

CONSTRUCTOR FUNCTION zipcode_obj_type

(SELF IN OUT NOCOPY ZIPCODE_OBJ_TYPE, zip VARCHAR2, city VARCHAR2,

MEMBER PROCEDURE get_zipcode_info

(out_zip OUT VARCHAR2, out_city OUT VARCHAR2, out_state OUT

VARCHAR2)

DBMS_OUTPUT.PUT_LINE ('Zip: ' ||in_zip_obj.zip);

DBMS_OUTPUT.PUT_LINE ('City: ' ||in_zip_obj.city);

DBMS_OUTPUT.PUT_LINE ('State: '||in_zip_obj.state);

After the map method is added to the object type, the object type instances may be compared

or ordered similar to the element datatypes For example, if V_ZIP_OBJ1 and V_ZIP_OBJ2 are two instances of the ZIPCODE_OBJ_TYPE, they can be compared like this:

v_zip_obj1 > v_zip_obj2

or

v_zip_obj1.zipcode() > v_zip_obj2.zipcode()

Note that the second statement uses dot notation to reference the map function.

Consider the following example, which demonstrates how the various object type methods created so far may be used:

v_zip_obj1 :=

zipcode_obj_type (zip => '12345',

city => 'Some City', state => 'AB');

v_zip_obj2 := zipcode_obj_type (zip => '48104');

Compare object instances via map methods

END IF;

END;

Note that when user-defined constructors are invoked, the call statements have no reference to the SELF default parameter.

When run, the script produces the following output:

v_zip_obj1 is not greater than v_zip_obj2

PL/SQL procedure successfully completed

ORDER METHODS

Order methods use a different technique when comparing and ordering object instances They

do not map object instances to an external axis such as NUMBER or DATE Instead, an order method compares the current object instance with another object instance of the same object type based on some criterion specified in the method.

An order method is a member function with a single IN parameter of the same object type that returns INTEGER as its return type Furthermore, the method must return a negative number, 0, or a positive number This number indicates that the object instance referenced by the SELF parameter is less than, equal to, or greater than the object instance referenced by the

IN parameter.

DID YOU KNOW?

The map and order methods have the following restrictions:

An object type may contain either an order or map method

An object type derived from another object type may not define an order method

Consider the following example of the order method for the zipcode_obj_type :

CONSTRUCTOR FUNCTION zipcode_obj_type

(SELF IN OUT NOCOPY ZIPCODE_OBJ_TYPE, zip VARCHAR2)RETURN SELF AS RESULT,

CONSTRUCTOR FUNCTION zipcode_obj_type

(SELF IN OUT NOCOPY ZIPCODE_OBJ_TYPE, zip VARCHAR2,city VARCHAR2, state VARCHAR2)

RETURN SELF AS RESULT,

MEMBER PROCEDURE get_zipcode_info

(out_zip OUT VARCHAR2, out_city OUT VARCHAR2,out_state OUT VARCHAR2),

STATIC PROCEDURE display_zipcode_info

(in_zip_obj IN ZIPCODE_OBJ_TYPE),ORDER MEMBER FUNCTION zipcode (zip_obj ZIPCODE_OBJ_TYPE)

RETURN INTEGER);

/

CREATE OR REPLACE TYPE BODY zipcode_obj_type AS

CONSTRUCTOR FUNCTION zipcode_obj_type

(SELF IN OUT NOCOPY zipcode_obj_type, zip VARCHAR2)

RETURN SELF AS RESULT

IS

BEGIN

SELF.zip := zip;

SELECT city, state

INTO SELF.city, SELF.state

CONSTRUCTOR FUNCTION zipcode_obj_type

(SELF IN OUT NOCOPY ZIPCODE_OBJ_TYPE, zip VARCHAR2, city VARCHAR2,

MEMBER PROCEDURE get_zipcode_info

(out_zip OUT VARCHAR2, out_city OUT VARCHAR2, out_state OUT

VARCHAR2)IS

DBMS_OUTPUT.PUT_LINE ('Zip: ' ||in_zip_obj.zip);

DBMS_OUTPUT.PUT_LINE ('City: ' ||in_zip_obj.city);

DBMS_OUTPUT.PUT_LINE ('State: '||in_zip_obj.state);

IF zip < zip_obj.zip THEN RETURN -1;

ELSIF zip = zip_obj.zip THEN RETURN 0;

ELSIF zip > zip_obj.zip THEN RETURN 1;

DBMS_OUTPUT.PUT_LINE ('v_zip_obj1 is greater than v_zip_obj2');ELSIF v_result = 0

THENDBMS_OUTPUT.PUT_LINE ('v_zip_obj1 is equal to v_zip_obj2');

ELSIF v_result = -1THEN

DBMS_OUTPUT.PUT_LINE ('v_zip_ob1 is less than v_zip_obj2');

END IF;

END;

In this script, the result of the order method is assigned to the v_result variable, defined as INTEGER Then, the decision is made based on the value of this variable.

When run, this script produces the following output:

The result of comparison is -1

v_zip_ob1 is less than v_zip_obj2

PL/SQL procedure successfully completed

L A B 2 3 2 E X E R C I S E S

This section provides exercises and suggested answers, with discussion related to how those answersresulted The most important thing to realize is whether your answer works You should figure out theimplications of the answers and what the effects are of any different answers you may come up with

23.2.1 Use Object Type Methods

In this exercise, you create various methods for the enrollment_obj_typeyou created in the

exercises portion of Lab 23.1 Note that before proceeding with this exercise, you need to drop the

nested table type you created in the preceding lab:

DROP TYPE enroll_tab_type;

Recall that you created enrollment_obj_typeas follows:

CREATE OR REPLACE TYPE ENROLLMENT_OBJ_TYPE AS OBJECT

(student_id NUMBER(8),first_name VARCHAR2(25),last_name VARCHAR2(25),course_no NUMBER(8),section_no NUMBER(3),enroll_date DATE,final_grade NUMBER(3));

Create the following methods for the enrollment_obj_type:

A) Create a user-defined constructor method that populates object type attributes by selecting datafrom the corresponding tables based on the incoming values for student ID, course, and sectionnumbers

ANSWER:The script should look similar to the following:

ch23_4a.sql, version 1.0

CREATE OR REPLACE TYPE enrollment_obj_type AS OBJECT

(student_id NUMBER(8),first_name VARCHAR2(25),last_name VARCHAR2(25),course_no NUMBER(8),section_no NUMBER(3),enroll_date DATE,final_grade NUMBER(3),CONSTRUCTOR FUNCTION enrollment_obj_type(SELF IN OUT NOCOPY enrollment_obj_type, in_student_id NUMBER,in_course_no NUMBER, in_section_no NUMBER)

RETURN SELF AS RESULT);

/

CREATE OR REPLACE TYPE BODY enrollment_obj_type AS

CONSTRUCTOR FUNCTION enrollment_obj_type

(SELF IN OUT NOCOPY enrollment_obj_type, in_student_id NUMBER,in_course_no NUMBER, in_section_no NUMBER)

RETURN SELF AS RESULT

IS

BEGIN

SELECT st.student_id, st.first_name, st.last_name, c.course_no,

se.section_no, e.enroll_date, e.final_gradeINTO SELF.student_id, SELF.first_name, SELF.last_name,SELF.course_no, SELF.section_no, SELF.enroll_date,SELF.final_grade

FROM student st, course c, section se, enrollment eWHERE st.student_id = e.student_id

AND c.course_no = se.course_noAND se.section_id = e.section_idAND st.student_id = in_student_id

AND c.course_no = in_course_noAND se.section_no = in_section_no;

enrollment_obj_type(st.student_id, st.first_name, st.last_name,

c.course_no, se.section_no, e.enroll_date,e.final_grade)

INTO v_enrollment_objFROM student st, course c, section se, enrollment eWHERE st.student_id = e.student_id

AND c.course_no = se.course_noAND se.section_id = e.section_idAND st.student_id = 102

AND c.course_no = 25AND se.section_no = 2;

Note that the SELECT INTO statement in the constructor body does not reference the

system-defined default constructor Instead, it uses the built-in SELF parameter to reference individualattributes of the current object instance

You may test the newly added constructor method as follows:

SET SERVEROUTPUT ON;