PLSQL Project Enhancement Semester 2 Teacher

8/13/2019 PLSQL Project Enhancement Semester 2 Teacher

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Oracle Academy 2 Database Programming with PL/SQL

Copyright 2010, Oracle. All rights reserved.

Sequence:

ASSESSMENT_ID_SEQ

Part 1: Procedures, Functions and Packages

In this section the students start by re-writing the anonymous blocks from MidTerm I to becomeprocedures and functions.

1. Find the file saved from called enroll_student_in_class.sqlfrom MidTerm I. Convert this toa procedure and have it accept a STU_ID and CLASS_ID as inputparameters. Use todays

date for the ENROLLMENT_DATE and the string Enrolled for the STATUS. Raise an

exception if the accepted student is already enrolled in the accepted class. In your exception

handler, display a message stating the student is already enrolled in the class.

Tables used: ENROLLMENTS

Topics Incorporated ==> Scalar variable; %TYPE, Procedure with IN parameters; INSERT;

COMMIT; Exception handling if provided stu_id is already enrolled in providedClass_id. This can be a user-defined exception which is raised after doing a SELECT

which is then followed by an IF statement.

To test, run twice, once to enroll the student and again to test the exception:

BEGIN

enroll_student_in_class(103, 3);END;

Suggested Solution:

--This procedure will enroll a student in a class.CREATE OR REPLACE PROCEDURE enroll_student_in_class

(p_stu_id IN enrollments.stu_id%TYPE,p_class_id IN enrollments.class_id%TYPE)

IS

v_times_enrolled PLS_INTEGER;

e_already_enrolled EXCEPTION;BEGIN

SELECT COUNT(*) INTO v_times_enrolled

FROM enrollments

WHERE class_id = p_class_id

AND stu_id = p_stu_id;IF v_times_enrolled 0

THEN RAISE e_already_enrolled;END IF;

INSERT INTO enrollments

(enrollment_date, class_id, stu_id, status)VALUES

(SYSDATE, p_class_id, p_stu_id, 'Enrolled');


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COMMIT;

EXCEPTION

WHEN e_already_enrolled THENDBMS_OUTPUT.PUT_LINE('Student ' || p_stu_id ||

' is already enrolled in class '|| p_class_id);

END enroll_student_in_class;

2. Find the file called drop_student_from_class.sqlfrom MidTerm I. Convert it to a procedurethat accepts a STU_ID and CLASS_ID as input parameters. If the DELETE fails because the

student is not in the class, raise a user_defined exception to display a message stating thestudent is not in the class.


Topics Incorporated ==> %TYPE; Procedure with IN parameters, DELETE;SQL%ROWCOUNT; COMMIT; User-defined exception.

To test, run twice, once to drop the student and again to test the exception:BEGIN

drop_student_from_class(103, 3);

END;

Suggested Solution:

-- This procedure will drop a student from a class.

CREATE OR REPLACE PROCEDURE drop_student_from_class

(p_stu_id IN enrollments.stu_id%TYPE,

p_class_id IN enrollments.class_id%TYPE)IS

e_not_enrolled EXCEPTION;

BEGINDELETE FROM enrollments

WHERE class_id = p_class_id AND stu_id = p_stu_id;

IF SQL%ROWCOUNT = 0 THENRAISE e_not_enrolled;

END IF;

COMMIT;

EXCEPTIONWHEN e_not_enrolled THEN

DBMS_OUTPUT.PUT_LINE('Student ' || p_stu_id ||

' is not enrolled in class '|| p_class_id);

END drop_student_from_class;


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3. Find the file calledstudent_class_list.sqlfrom MidTerm I. Rewrite it to be a procedure thatdisplays all of the classes a student has been enrolled in within the most recent 10 years. For

example: If you run your procedure on May 10, 2010, you should display all enrollmentsbetween May 10, 2000 and May 10, 2010. Accept the STU_ID as an input parameter. For

each enrollment, display the ENROLLMENT_DATE, CLASS_ID and STATUS.

Tables used: ENROLLMENTSTopics Incorporated ==> %TYPE; Procedure with IN parameters; SYSDATE,

ADD_MONTHS, Explicit cursor to find all courses for the provided Student

ID;DBMS_OUTPUT to display the list of classes.

To test:

BEGIN

student_class_list(101);END;

Suggested Solution:

-- This procedure will list all students in a class.

CREATE OR REPLACE PROCEDURE student_class_list(p_stu_id IN enrollments.stu_id%TYPE)

IS

CURSOR stu_class_cur ISSELECT enrollment_date, class_id, status

FROM enrollments

WHERE stu_id = p_stu_id

AND enrollment_datebetween ADD_MONTHS (SYSDATE,-120) and SYSDATE;

BEGIN

DBMS_OUTPUT.PUT_LINE('Student ' || p_stu_id ||' is enrolled in the following classes:');

FOR stu_class_rec IN stu_class_cur LOOP

DBMS_OUTPUT.PUT_LINE('Class: ' ||stu_class_rec.class_id ||' Enrolled on: ' || stu_class_rec.enrollment_date ||

' and has a status of: '|| stu_class_rec.status );

END LOOP;

END student_class_list;


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4. Find the file called add_new_classes.sqlfrom MidTerm I. Rewrite it as a Procedure and haveit accept the following IN parameters:

a. number of new classes required. Set a default value of 1.b. Course id; For each new class, use todayas the START_DATE.c. Period, to specify what days the class meets.d.

Frequency, to specify how often it meets.e. Instructor id, to specify who is teaching the class(s).

Note for the teacher:It is probably more likely and safer to use a sequence number for the

class_id. If 2 sessions are calling this procedure at the same time, there is a small chance thesame MAX(class_id) could be found. This would cause the second set of INSERTS to fail.

The first option will work for this project, but you might discuss this interesting subtlety with

your students.

Tables used: CLASSES

Topics Incorporated ==> Creating a procedure; SELECT; INSERT; COMMIT;

DEFAULT value; Using a LOOP to only insert n new rows.

To test:

BEGIN

add_new_classes (2, 1001, 'TUE_TR', 'Once', 3003) ;END;

Suggested Solution 1:

CREATE OR REPLACE PROCEDURE add_new_classes

(p_number_new_classes IN PLS_INTEGER DEFAULT 1,

p_course_id IN classes.course_id%TYPE,p_period IN classes.period%TYPE,

p_frequency IN classes.frequency%TYPE,

p_instr_id IN classes.instr_id%TYPE )IS

v_current_max_class_id classes.class_id%TYPE;

BEGINSELECT MAX(class_id)

INTO v_current_max_class_id

FROM classes;

FOR loop_counter IN 1..p_number_new_classes LOOPINSERT INTO classes (class_id, start_date,course_id,

period, frequency,instr_id)

VALUES (v_current_max_class_id + loop_counter, SYSDATE,

p_course_id, p_period, p_frequency, p_instr_id);COMMIT;

END LOOP;

END add_new_classes;


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SELECT MAX(class_id)

FROM classes;

DROP SEQUENCE class_id_seq;CREATE SEQUENCE class_id_seq

START WITH (number_returned_from_SELECT + 1)

INCREMENT BY 1NOCACHE;

CREATE OR REPLACE PROCEDURE add_new_classes

(p_number_new_classes IN PLS_INTEGER DEFAULT 1,p_course_id IN classes.course_id%TYPE,

p_period IN classes.period%TYPE,

p_frequency IN classes.frequency%TYPE,p_instr_id IN classes.instr_id%TYPE )

IS

BEGIN

FOR loop_counter IN 1..p_number_new_classes LOOPINSERT INTO classes (class_id, start_date,course_id,

period, frequency,instr_id)

VALUES (class_id_seq.NEXTVAL,SYSDATE, p_course_id,p_period,p_frequency,p_instr_id);

COMMIT;

END LOOP;

END add_new_classes;

5. Find the file called course_roster.sqlfrom MidTerm I and rewrite it as a procedure. Acceptthe INSTR_ID and COURSE_ID as input parameters. For each ENROLLMENT, display:

CLASS_ID, STATUS, Student FIRST_NAME and LAST_NAME.

Tables used: ENROLLMENTS; CLASSES; STUDENTS

Topics Incorporated ==> SELECT with JOIN; Explicit Cursor

To test:BEGIN

course_roster(3003, 1002);

END;


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Suggested Solution:

CREATE OR REPLACE PROCEDURE course_roster(p_instr_id IN classes.instr_id%TYPE,

p_course_id IN classes.course_id%TYPE)

ISCURSOR stu_course_cur ISSELECT e.class_id, e.status, s.first_name, s.last_name

FROM enrollments e, classes c, students s

WHERE e.class_id = c.class_idAND e.stu_id = s.stu_id

AND c.course_id = p_course_id

AND c.instr_id = p_instr_id;

BEGINDBMS_OUTPUT.PUT_LINE('Course ' || p_course_id ||

' has the following students:');

FOR stu_course_rec IN stu_course_cur LOOPDBMS_OUTPUT.PUT_LINE('Class: ' || stu_course_rec.class_id

|| ' Student: '|| stu_course_rec.first_name || ' ' ||

stu_course_rec.last_name ||

' with a status of: ' || stu_course_rec.status );END LOOP;

END course_roster;

6. Find the file called convert_grade.sqlfrom MidTerm I and rewrite it to be a function Use anIN parameter to enter the number grade. RETURN a CHAR value. Use the following rules:

A:90 or above, B: >=80 and=70 and < 80, D: >=60 and < 70, F: Scalar variables...NUMBER IN; CHAR RETURNED; IF or CASEStatement (A=90 to 100, B=80-90, C=70-80, D=60-70, F=


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CREATE OR REPLACE FUNCTION convert_grade(p_numeric_grade IN NUMBER)

RETURN varchar2

ISv_letter_grade CHAR(1);BEGIN

IF p_numeric_grade >= 90.0 THEN

v_letter_grade := 'A';ELSIF p_numeric_grade >= 80.0 THEN

v_letter_grade := 'B';

ELSIF p_numeric_grade >= 70.0 THEN

v_letter_grade := 'C';ELSIF p_numeric_grade >= 60.0 THEN

v_letter_grade := 'D';

ELSE v_letter_grade := 'F';END IF;

RETURN v_letter_grade;

END convert_grade;


CREATE OR REPLACE FUNCTION convert_grade(p_numeric_grade IN NUMBER)

RETURN varchar2

IS

v_letter_grade CHAR(1);BEGIN

v_letter_grade :=

CASE WHEN p_numeric_grade >= 90.0 THEN 'A'WHEN p_numeric_grade >= 80.0 THEN 'B'

WHEN p_numeric_grade >= 70.0 THEN 'C'

WHEN p_numeric_grade >= 60.0 THEN 'D'ELSE 'F'

END;

RETURN v_letter_grade;

END convert_grade;


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7. Find the file calledstudent_count.sqland rewrite it as a function that will RETURN thenumber of students in a particular class. Accept a CLASS_ID as an IN parameter.


Topics Incorporated ==> Scalar variable...INTEGER; SELECT COUNT(*) INTO variable

FROM enrollments where class_id = ...; using a user-defined function in SQL.

Testing the function:

SELECT class_id, student_count(class_id) AS "Student Count", stu_idFROM enrollments;

Suggested Solution:

CREATE OR REPLACE FUNCTION student_count

(p_class_id IN classes.class_id%TYPE)

RETURN NUMBERIS

v_student_count PLS_INTEGER;

BEGIN

SELECT COUNT(*)INTO v_student_count

FROM enrollments

WHERE class_id = p_class_id;RETURN v_student_count;

END student_count;

8. Create a package called enrollments_packagewhich will contain the procedures you createdin A, B, and C. Make all procedures public. Comment your procedures to explain their

purpose and functionality.


Topics Incorporated ==> Creating a package; incorporating comments.

Suggested Solution:

--PACKAGE SPEC

CREATE OR REPLACE PACKAGE enrollments_packageIS

-- This procedure will enroll a student in a class.

PROCEDURE enroll_student_in_class(p_stu_id IN enrollments.stu_id%TYPE,

p_class_id IN enrollments.class_id%TYPE ) ;

-- This procedure will drop a student from a class


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PROCEDURE drop_student_from_class


p_class_id IN enrollments.class_id%TYPE);-- This procedure will list all students in a class

PROCEDURE student_class_list

(p_stu_id IN enrollments.stu_id%TYPE);END enrollments_package;

--PACKAGE BODY

CREATE OR REPLACE PACKAGE BODY enrollments_package

IS


PROCEDURE enroll_student_in_class(p_stu_id IN enrollments.stu_id%TYPE,

p_class_id IN enrollments.class_id%TYPE)

ISv_times_enrolled PLS_INTEGER;

e_already_enrolled EXCEPTION;

BEGIN

SELECT COUNT(*) INTO v_times_enrolledFROM enrollments

WHERE class_id = p_class_id

AND stu_id = p_stu_id;IF v_times_enrolled 0

THEN RAISE e_already_enrolled;

END IF;

INSERT INTO enrollments(enrollment_date, class_id, stu_id, status)

VALUES

(SYSDATE, p_class_id, p_stu_id, 'Enrolled');COMMIT;

EXCEPTION

WHEN e_already_enrolled THENDBMS_OUTPUT.PUT_LINE('Student ' || p_stu_id ||

' is already enrolled in class '|| p_class_id);

END enroll_student_in_class;






BEGINDELETE FROM enrollments


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WHERE class_id = p_class_id AND stu_id = p_stu_id;

IF SQL%ROWCOUNT = 0 THEN RAISE e_not_enrolled; END IF;

COMMIT;EXCEPTION

WHEN e_not_enrolled THEN

DBMS_OUTPUT.PUT_LINE('Student ' || p_stu_id ||' is not enrolled in class '|| p_class_id);END drop_student_from_class;

-- This procedure will list all students in a classPROCEDURE student_class_list

(p_stu_id IN enrollments.stu_id%TYPE)

IS

CURSOR stu_class_cur ISSELECT enrollment_date, class_id, status

FROM enrollments

WHERE stu_id = p_stu_idAND enrollment_date

between ADD_MONTHS (SYSDATE,-120) and SYSDATE;

BEGIN

DBMS_OUTPUT.PUT_LINE('Student ' || p_stu_id ||' is enrolled in the following classes:');


DBMS_OUTPUT.PUT_LINE('Class: ' ||stu_class_rec.class_id || ' Enrolled on: ' ||stu_class_rec.enrollment_date ||


END LOOP;


END enrollments_package;

9. Find the program saved in the file create_assignment.sql.Rewrite it as a procedure thataccepts the assignment description as an input parameter.

Tables used: ASSESSMENTS

Topics Incorporated ==> SQL INSERT; IN Argument, Use of sequence in INSERT;

To test:BEGIN

create_assignment('this is to test the procedure');

END;


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11.Rewrite the program stored in the fileshow_missing_grades.sql to be a procedure. Accept astart_date and end_date to establish a date range. Display only enrollments between those

two dates. Write your procedure so the start_date and end_date are optional. If both dates arenot entered, display all applicable enrollments for the past year, and include a note about the

date range. For each enrollment, list the CLASS_ID, STU_ID, and STATUS. Order the

output by ENROLLMENT_DATE with the most recent enrollments first.


Topics Incorporated ==> SQL with BETWEEN; Dates; Default values with IN parameters,

NULL values in a database column, MONTHS_BETWEEN or other way to find the pastyear.

To test:

BEGINshow_missing_grades('01-AUG-01', '01-AUG-05');

END;

Suggested Solution:

CREATE OR REPLACE PROCEDURE show_missing_grades

(p_start_date IN DATE DEFAULT NULL,p_end_date IN DATE DEFAULT NULL)

IS

CURSOR no_grades_cur ISSELECT class_id, stu_id, status

FROM enrollments

WHERE final_numeric_grade IS NULL

AND final_letter_grade IS NULLAND enrollment_date BETWEEN p_start_date AND

p_end_date

ORDER BY enrollment_date DESC;v_start_date DATE;

v_end_date DATE;

BEGINIF p_start_date IS NULL OR p_end_date IS NULL

THEN

v_start_date := ADD_MONTHS(SYSDATE,-12);

v_end_date := SYSDATE;DBMS_OUTPUT.PUT_LINE

('You have not specified both dates. The listing will

show all enrollments for the past year.');

ELSEv_start_date :=p_start_date;

v_end_date := P_end_date;

END IF;DBMS_OUTPUT.PUT_LINE


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('Date range: Between ' || v_start_date || ' and ' ||

v_end_date || '.');

DBMS_OUTPUT.PUT_LINE('The following enrollments have no grade.');

FOR no_grades_rec IN no_grades_cur LOOP

DBMS_OUTPUT.PUT_LINE ('Class ID ' ||no_grades_rec.class_id || 'Student ID ' ||no_grades_rec.stu_id || ' with a status of: '

||no_grades_rec.status);

END LOOP;END show_missing_grades;

12.Find the file called compute_average_grade.sqland rewrite it as a function. Accept aCLASS_ID. Return the average grade.

Tables used: ENROLLMENTSTopics Incorporated ==> SQL with AVG function

To test: (there will be no output since there are no final grades in the table)

DECLAREv_grade NUMBER;

BEGIN

v_grade := compute_average_grade(6);DBMS_OUTPUT.PUT_LINE(v_grade);

END;

Suggested Solution:

CREATE OR REPLACE FUNCTION compute_average_grade

(p_class_id IN enrollments.class_id%TYPE)RETURN NUMBER

IS

v_avg_grade enrollments.final_numeric_grade%TYPE;BEGIN

SELECT AVG(final_numeric_grade)

INTO v_avg_grade

FROM enrollmentsWHERE class_id = p_class_id;

RETURN v_avg_grade;

END compute_average_grade;


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13.Find the file called count_classes_per_course.sql and rewrite it as a function. Accept aCOURSE_ID. Return the number of classes offered for that course.

Tables used: CLASSES

Topics Incorporated ==> SQL SELECT with COUNT.

To test:

DECLARE

v_classes PLS_INTEGER;BEGIN

v_classes := count_classes_per_course(1001);

DBMS_OUTPUT.PUT_LINE(v_classes);

END;

Suggested Solution:

CREATE OR REPLACE FUNCTION count_classes_per_course

(p_course_id IN classes.course_id%TYPE)

RETURN NUMBER

ISnum_classes PLS_INTEGER;

BEGIN

SELECT COUNT(*)INTO v_num_classes

FROM classes

WHERE course_id = p_course_id;

RETURN v_num_classes;END count_classes_per_course;

14.Convert the fileshow_class_offerings.sql to a procedure. Accept a start date and end date.For each class found, display the CLASS_ID, START_DATE, instructor FIRST_NAME and

LAST_NAME, course TITLE and SECTION_CODE, and average grade. Find the average

grade by a call to the function compute_average_grade.

Tables used: CLASSES, INSTRUCTORS, COURSES,ENROLLMENTS

Topics Incorporated ==> Calling a function from a procedure; using dates; SQL

Join; %TYPE.

To test:

BEGIN

show_class_offerings('01-AUG-01','01-AUG-06');END;


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Suggested Solution:

CREATE OR REPLACE PROCEDURE show_class_offerings(p_start_date IN DATE,

p_end_date IN DATE)

ISv_avg_grade NUMBER;CURSOR classes_info_cur IS

SELECT cl.class_id, cl.start_date,

i.first_name, i.last_name,cour.title, cour.section_code

FROM classes cl, courses cour, instructors i

WHERE start_date BETWEEN p_start_date AND p_end_date

AND cl.course_id = cour.course_idAND cl.instr_id = i.instructor_id

ORDER BY 1,2,4;

BEGINDBMS_OUTPUT.PUT_LINE

('Date range: Between ' || p_start_date || ' and ' ||

p_end_date || '.');

DBMS_OUTPUT.PUT_LINE('Classes Information.');

FOR classes_info_rec IN classes_info_cur LOOP

-- call the compute_average_grade functionv_avg_grade := compute_average_grade (classes_info_rec.class_id);

DBMS_OUTPUT.PUT_LINE (

'Class ID ' || classes_info_rec.class_id ||

'Average Grade '|| v_avg_grade ||' - Start Date ' || classes_info_rec.start_date ||

'Instructor ' || classes_info_rec.first_name || ' ' || classes_info_rec.last_name ||

'Course Title '|| classes_info_rec.title ||'Offering Section ' || classes_info_rec.section_code );

END LOOP;

END show_class_offerings;

15.Create a package called admin_tools_packageincorporating procedure and functions youwrote in steps K to N. Make the following public:show_missing_grades,

show_class_offerings, count_classes_per_course. Make the following private:compute_average_grade.

Tables used: CLASSES, INSTRUCTORS, COURSES

Topics Incorporated: Creating a package; Public vs. Private package constructs.


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--PACKAGE SPEC

CREATE OR REPLACE PACKAGE admin_tools_packageIS

-- This procedure will show missing grades for a class.PROCEDURE show_missing_grades(p_start_date IN DATE DEFAULT ADD_MONTHS(SYSDATE,-12),

p_end_date IN DATE DEFAULT SYSDATE);

-- This procedure will list classes offered

PROCEDURE show_class_offerings

(p_start_date IN DATE,

p_end_date IN DATE);

-- This function will count the number of classes per course.

FUNCTION count_classes_per_course(p_course_id IN classes.course_id%TYPE)

RETURN NUMBER;

END admin_tools_package;

--PACKAGE BODY

CREATE OR REPLACE PACKAGE BODY admin_tools_package

IS

--This function is private in this package and it will compute--the average grade for a class.

FUNCTION compute_average_grade


IS

v_avg_grade enrollments.final_numeric_grade%TYPE;BEGIN

SELECT AVG(final_numeric_grade)

INTO v_avg_grade


RETURN v_avg_grade;


--This procedure will show missing grades for a class.

--------------------------------------------------------

PROCEDURE show_missing_grades(p_start_date IN DATE DEFAULT ADD_MONTHS(SYSDATE,-12),


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p_end_date IN DATE DEFAULT SYSDATE)

IS


FROM enrollments

WHERE final_numeric_grade IS NULLAND final_letter_grade IS NULLAND enrollment_date BETWEEN p_start_date AND

p_end_date

ORDER BY enrollment_date DESC;BEGIN

IF p_start_date IS NULL OR p_end_date IS NULL

THEN

DBMS_OUTPUT.PUT_LINE('You have not specified both dates. The listing will show all enrollments for the past

year.');


('Date range: Between ' || p_start_date || ' and ' || p_end_date || '.');

DBMS_OUTPUT.PUT_LINE

('The following enrollments have no grade.');FOR no_grades_rec IN no_grades_cur LOOP

DBMS_OUTPUT.PUT_LINE ('Class ID ' || no_grades_rec.class_id || 'Student ID ' ||

no_grades_rec.stu_id || ' with a status of: ' ||no_grades_rec.status);END LOOP;

END show_missing_grades;

--This procedure will list classes offered--------------------------------


(p_start_date IN DATE,p_end_date IN DATE)

ISv_avg_grade NUMBER;

CURSOR classes_info_cur IS


i.first_name, i.last_name,cour.title, cour.section_code

FROM classes cl, courses cour, instructors i

WHERE start_date BETWEEN p_start_date and p_end_date


ORDER BY 1,2,4;

--BEGIN


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('Date range: Between ' || p_start_date || ' and ' || p_end_date || '.');

DBMS_OUTPUT.PUT_LINE('Classes Information.');


v_avg_grade := compute_average_grade(classes_info_rec.class_id);DBMS_OUTPUT.PUT_LINE (


'Average Grade '|| v_avg_grade ||' - Start Date ' || classes_info_rec.start_date ||

'Instructor ' || classes_info_rec.first_name || ' ' ||

classes_info_rec.last_name ||

'Course Title '|| classes_info_rec.title ||'Offering Section ' || classes_info_rec.section_code );

END LOOP;


--This function will count the number of classes per course.

------------------------------------------------------


RETURN NUMBER

ISv_num_classes PLS_INTEGER;

BEGIN

SELECT COUNT(*)

INTO v_num_classesFROM classes


RETURN v_num_classes;END count_classes_per_course;



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Part 2: Managing Students and Grades (enrollments_package)

The enrollments_packageyou created in Part 1 contains the following public procedures:

1. Procedure enroll_student_in_class(p_stu_id IN enrollments.stu_id%TYPE, p_class_id INenrollments.class_id%TYPE)

2. Procedure drop_student_from_class(p_stu_id IN enrollments.stu_id%TYPE, p_class_id INenrollments.class_id%TYPE)

3. Procedurestudent_class_list(p_stu_id IN enrollments.stu_id%TYPE)

The Assignment and Deliverables:Modify thestudent_class_list procedure in the package, to add the following functionality:

1. Utilize the overloading feature of the PLSQL package, to overload thestudent_class_listprocedure as follows:

When the STU_ID parameter is passed, the procedure should display a list of classes inwhich the student has been enrolled, within the most recent 6 years.

When the procedure is called without a parameter, the procedure should display a list ofclasses for all students in which they have been enrolled, within the most recent 6 years.

2. Create a procedure read_external_file, to read an external text file stored outside the databaseas an operating system text file. Use DBMS_OUTPUT to display the content of the external

file.

The external file is named student_class_list.txtand is stored in the operating system

directory referenced by the Oracle directory object 'WF_FLAGS'.

Your output should look something like this:

Enrollment Report

Student Id Enrollment Date Class id101 12-AUG-04 1

102 12-AUG-04 1

103 12-AUG-04 1104 12-AUG-04 1

*** END OF REPORT ***

Hints: The Exceptions used with UTL_FILE.GET_LINE: INVALID_FILEHANDLE INVALID_OPERATION READ_ERROR NO_DATA_FOUND VALUE_ERROR

Directory object name is: 'WF_FLAGS' and must be referenced in capital letters.


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Incorporated Topics for problems 1 and 2:

Overloading procedures in a package. Reading external files with the UTL_FILE package. Students must use a Directory object WF_FLAGS that is part of the standard course setup.

Oracle Directory names are case sensitive, so the students must type it in exactly as above.

Oracle Corporation security rules do allow Academy participants to read but not createexternal text files (using UTL_FILE) on database server machines. This is why the text filestudent_class_list.txt is provided for you.

To test:

BEGIN

enrollments_package.read_external_file;

END;

Part 2: Suggested Solution

--PACKAGE SPEC

CREATE OR REPLACE PACKAGE enrollments_packageIS

-- This procedure will enroll a student in a class.PROCEDURE enroll_student_in_class

(p_stu_id IN enrollments.stu_id%TYPE,p_class_id IN enrollments.class_id%TYPE ) ;


PROCEDURE drop_student_from_class(p_stu_id IN enrollments.stu_id%TYPE,

p_class_id IN enrollments.class_id%TYPE);

-- Overloaded procedure will list Enrollment date and class ids for a student

PROCEDURE student_class_list(p_stu_id IN enrollments.stu_id%TYPE);

-- Overloaded procedure will list Enrollment date and class ids for all students

PROCEDURE student_class_list;

PROCEDURE read_external_file;



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--PACKAGE BODY

CREATE OR REPLACE PACKAGE BODY enrollments_packageIS


PROCEDURE enroll_student_in_class



v_times_enrolled PLS_INTEGER;

e_already_enrolled EXCEPTION;

BEGINSELECT COUNT(*) INTO v_times_enrolled

FROM enrollments

WHERE class_id = p_class_idAND stu_id = p_stu_id;

IF v_times_enrolled 0

THEN RAISE e_already_enrolled;END IF;

INSERT INTO enrollments (enrollment_date, class_id, stu_id,status)

VALUES( SYSDATE, p_class_id, p_stu_id, 'Enrolled');

COMMIT;

EXCEPTIONWHEN e_already_enrolled THEN

DBMS_OUTPUT.PUT_LINE('Student ' || p_stu_id ||

' is already enrolled in class '|| p_class_id);END enroll_student_in_class;






BEGIN

DELETE FROM enrollmentsWHERE class_id = p_class_id AND stu_id = p_stu_id;

IF SQL%ROWCOUNT = 0 THEN RAISE e_not_enrolled; END IF;

COMMIT;EXCEPTION


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WHEN e_not_enrolled THEN

DBMS_OUTPUT.PUT_LINE('Student ' || p_stu_id ||' is not enrolled in class '|| p_class_id);

END drop_student_from_class;

-- This procedure will list a students enrollments

-- Overloaded procedure with one parameter


(p_stu_id IN enrollments.stu_id%TYPE)

ISCURSOR stu_class_cur IS

SELECT enrollment_date, class_id, status

FROM enrollments

WHERE stu_id = p_stu_idAND enrollment_date

BETWEEN ADD_MONTHS (SYSDATE,-72) and SYSDATE;

BEGINDBMS_OUTPUT.PUT_LINE('Student ' || p_stu_id ||

' is enrolled in the following classes:');


DBMS_OUTPUT.PUT_LINE('Class: ' ||stu_class_rec.class_id || ' Enrolled on: ' ||stu_class_rec.enrollment_date ||


END LOOP;END student_class_list;

-- This procedure will list all students

-- Overloaded procedure with no parameter


IS

CURSOR stu_class_cur IS

SELECT enrollment_date, class_id, status, stu_idFROM enrollments

WHERE enrollment_date

BETWEEN ADD_MONTHS (SYSDATE,-72) and SYSDATE

ORDER BY stu_id, enrollment_date ,class_id;

BEGIN

DBMS_OUTPUT.PUT_LINE('Students are enrolled in the following classes:');

FOR stu_class_rec IN stu_class_cur LOOPDBMS_OUTPUT.PUT_LINE('Student: ' || stu_class_rec.stu_id || ' Class: '

||stu_class_rec.class_id || ' Enrolled on: ' || stu_class_rec.enrollment_date ||

' and has a status of: '|| stu_class_rec.status );END LOOP;


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--Procedure read_external_file to read and display an external operating system text file.--

PROCEDURE read_external_file

ISfile UTL_FILE.FILE_TYPE;v_line varchar2(1024);

BEGIN--the number of bytes returned will be 1024 or less if a line terminator is seen.

file := UTL_FILE.FOPEN ('WF_FLAGS', 'student_class_list.txt', 'r');

-- Nested Block to handle end of file errors locally.

BEGINLOOP

UTL_FILE.GET_LINE(file , v_line);

DBMS_OUTPUT.PUT_LINE( v_line );END LOOP;

EXCEPTION

WHEN NO_DATA_FOUND THEN

NULL;END;

EXCEPTION

--If no text was read due to end of file, the NO_DATA_FOUND exception is raisedWHEN NO_DATA_FOUND THEN

RAISE_APPLICATION_ERROR(-20005, 'END OF FILE.');

WHEN UTL_FILE.INVALID_FILEHANDLE THENRAISE_APPLICATION_ERROR(-20006,'Invalid File.');

WHEN UTL_FILE.INVALID_OPERATION THENRAISE_APPLICATION_ERROR (-20007, 'Unable to read or operate as requested.');

WHEN UTL_FILE.READ_ERROR THENRAISE_APPLICATION_ERROR (-20008, 'Unable to read the file.');

END read_external_file;



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Part 3: School Administrators Tools (admin_tools_package)

The admin_tools_packageyou created in Part I contains the following programs:

1. Procedureshow_missing_grades(p_start_date IN DATE DEFAULT NULL,p_end_date IN DATE DEFAULT NULL)2. Procedureshow_class_offerings (p_start_date IN DATE, p_end_date IN DATE)3. Function count_classes_per_course (p_course_id IN classes.course_id%TYPE) RETURN

NUMBER

4. Function compute_average_grade (p_class_id IN enrollments.class_id%TYPE) RETURNNUMBER

This function is private in this package.

The Assignment and Deliverables:

1. Utilize the forward declaration concept to be able to move the body of the private functioncompute_average_gradeto anywhere in the package body. Recompile and test the package.To test:

BEGIN

admin_tools_package.show_class_offerings('01-AUG-01','01-AUG-06');

END;


--PACKAGE SPEC

CREATE OR REPLACE PACKAGE admin_tools_package

IS

-- This procedure will show missing grades for a class.

PROCEDURE show_missing_grades(p_start_date IN DATE DEFAULT NULL,p_end_date IN DATE DEFAULT NULL);

-- This procedure will list classes offeredPROCEDURE show_class_offerings

(p_start_date IN DATE,p_end_date IN DATE);

-- This function will count the number of classes per course.

FUNCTION count_classes_per_course

(p_course_id IN classes.course_id%TYPE)RETURN NUMBER;


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--PACKAGE BODY

CREATE OR REPLACE PACKAGE BODY admin_tools_package

IS

--This function is private in this package and it will compute

--The average grade for a class.

--Forward Declaration

FUNCTION compute_average_grade (p_class_id IN enrollments.class_id%TYPE)

RETURN NUMBER;

--This procedure will show missing grades for a class.

----------------------------------------------------

PROCEDURE show_missing_grades(p_start_date IN DATE DEFAULT NULL,

p_end_date IN DATE DEFAULT NULL)

IS


FROM enrollments

WHERE final_numeric_grade IS NULLAND final_letter_grade IS NULL

AND enrollment_date BETWEEN p_start_date AND

p_end_date

ORDER BY enrollment_date DESC;v_start_date DATE;

v_end_date DATE;

BEGINIF p_start_date IS NULL OR p_end_date IS NULL

THEN

v_start_date := ADD_MONTHS(SYSDATE,-12);v_end_date := SYSDATE;


('You have not specified both dates. The listing will

show all enrollments for the past year.');ELSE

v_start_date :=p_start_date;

v_end_date := P_end_date;


('Date range: Between ' || v_start_date || ' and ' ||

v_end_date || '.');DBMS_OUTPUT.PUT_LINE


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('The following enrollments have no grade.');

FOR no_grades_rec IN no_grades_cur LOOP

DBMS_OUTPUT.PUT_LINE ('Class ID ' ||no_grades_rec.class_id || 'Student ID ' ||

no_grades_rec.stu_id || ' with a status of: '

||no_grades_rec.status);END LOOP;END show_missing_grades;

--This procedure will list classes offered----------------------------------


(p_start_date IN DATE,

p_end_date IN DATE)

IS

v_avg_grade NUMBER;CURSOR classes_info_cur IS


i.first_name, i.last_name,

cour.title, cour.section_codeFROM classes cl, courses cour, instructors i

WHERE start_date BETWEEN p_start_date AND p_end_date


ORDER BY 1,2,4;

--

BEGINDBMS_OUTPUT.PUT_LINE

('Date range: Between ' || p_start_date || ' AND ' || p_end_date || '.');

DBMS_OUTPUT.PUT_LINE ('Classes Information.');


v_avg_grade := compute_average_grade (classes_info_rec.class_id);DBMS_OUTPUT.PUT_LINE (


'Average Grade '|| v_avg_grade ||

' - Start Date ' || classes_info_rec.start_date ||'Intructor ' || classes_info_rec.first_name || ' ' ||

classes_info_rec.last_name ||

'Course Title '|| classes_info_rec.title ||

'Offering Section ' || classes_info_rec.section_code );END LOOP;



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--This function will count the number of classes per course.


RETURN NUMBER

ISv_num_classes PLS_INTEGER;BEGIN

SELECT COUNT(*)

INTO v_num_classesFROM classes


RETURN v_num_classes;

END count_classes_per_course;

FUNCTION compute_average_grade


IS

v_avg_grade enrollments.final_numeric_grade%TYPE;

BEGINSELECT AVG(final_numeric_grade)

INTO v_avg_grade


RETURN v_avg_grade;



Part 4: Create Database Triggers

1. Create thegrade_change_historytable as follows:CREATE TABLE grade_change_history

(time_stamp DATE,

stu_id NUMBER(7,0),

class_id NUMBER(6,0),

enroll_date DATE,old_final_grade CHAR(1),

new_final_grade CHAR(1));

2. Create a row level trigger audit_grade_changeto keep a history of all the changes made tostudents final letter grade. The grade change is recorded every time theFINAL_LETTER_GRADE field is updated in the ENROLLMENTS table.


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Every time the trigger is fired, it should insert a record in theGRADE_CHANGE_HISTORY table, recording the old grade and the new grade for each

student.

Test your trigger by updating the final_letter_grade for a student, in theENROLLMENTS table.

Topics Incorporated: Row level DML triggerTables Used: ENROLLMENTS, GRADE_CHANGE_HISTORY

To test:1. UPDATE enrollments

SET final_letter_grade = 'A'

WHERE stu_id = 101;

2. SELECT * FROM grade_change_history;


--Trigger Code

------------------

CREATE OR REPLACE TRIGGER audit_grade_change

AFTER UPDATE OF final_letter_grade ON enrollments

FOR EACH ROW

BEGININSERT INTO grade_change_history(time_stamp,stu_id, class_id,enroll_date, old_final_grade, new_final_grade)

VALUES(SYSDATE,

:OLD.stu_id,:OLD.class_id,

:OLD.enrollment_date,

:OLD.final_letter_grade,

:NEW.final_letter_grade);END;


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Part 5: Create manage_triggers_package

The Assignment and Deliverables:

1. Create a package manage_triggers_package that contains two overloaded functions calledmanage_triggers. The functions are invoked to disable/enable all triggers for a table, or tocompile a trigger.

Use Native Dynamic SQL to execute the DDL commands programmatically. Code an exception handling block to display a message if the DDL command fails.Use the following guidelines:

When the function is called with two parameters: manage_triggers (p_tablename,p_action)

Pass a table name to P_TABLENAME parameter. Pass disable or enable string to P_ACTION parameter.

When the function is called with only one parameter manage_triggers (p_trigger_name) Pass a trigger name to P_TRIGGER_NAME parameter.

Hints:

Use the ALTER TABLE command to disable/enable all triggers of a tableprogrammatically.

Use the ALTER TRIGGER command to compile the trigger programmatically.Topics Incorporated: Forward Declaration, Native Dynamic SQL, Overloading, exception

handling.

Tables used: CLASSES, INSTRUCTORS, COURSES

To test: -Pass a table name to P_TABLENAME parameter

-Pass disable or enable string to P_ACTION parameter.

-Pass a trigger name to P_TRIGGER_NAME parameter.

BEGIN

manage_triggers_package.manage_triggers('ENROLLMENTS', 'ENABLE');

END;

BEGIN

manage_triggers_package.manage_triggers('audit_grade_change');END;


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--Create a new package to manage the database triggers.

--PACKAGE SPEC

CREATE OR REPLACE PACKAGE manage_triggers_packageIS

PROCEDURE manage_triggers(p_tablename IN VARCHAR2, p_mode IN

VARCHAR2);

PROCEDURE manage_triggers(p_trigger_name IN VARCHAR2);

END manage_triggers_package;

--PACKAGE BODY

CREATE OR REPLACE PACKAGE BODY manage_triggers_package

IS

--Overloaded Procedure manage triggers------------------------------

PROCEDURE manage_triggers(p_tablename IN VARCHAR2, p_mode IN

VARCHAR2)IS

BEGIN

EXECUTE IMMEDIATE 'ALTER TABLE '||p_tablename||' '|| p_mode || ' All TRIGGERS';

DBMS_OUTPUT.PUT_LINE(p_tablename || ' Altered.');

EXCEPTION

WHEN OTHERS THENRAISE_APPLICATION_ERROR(-20001,'DDL Command Failed.');

END;

--Overloaded Procedure manage triggers

------------------------------

PROCEDURE manage_triggers(p_trigger_name IN VARCHAR2)

ISBEGIN

EXECUTE IMMEDIATE 'ALTER TRIGGER '||p_trigger_name|| '

COMPILE';

DBMS_OUTPUT.PUT_LINE(p_trigger_name|| ' Trigger Compiled. ');

EXCEPTIONWHEN OTHERS THEN


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RAISE_APPLICATION_ERROR(-20001,'DDL Command Failed.');

END;

END manage_triggers_package;

PLSQL Project Enhancement Semester 2 Teacher

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