PL/SQL block problem: No data found error - sql

Question

SET SERVEROUTPUT ON
DECLARE
v_student_id NUMBER := &sv_student_id;
v_section_id NUMBER := 89;
v_final_grade NUMBER;
v_letter_grade CHAR(1);
BEGIN
SELECT final_grade
INTO v_final_grade
FROM enrollment
WHERE student_id = v_student_id
AND section_id = v_section_id;
CASE -- outer CASE
WHEN v_final_grade IS NULL THEN
DBMS_OUTPUT.PUT_LINE ('There is no final grade.');
ELSE
CASE -- inner CASE
WHEN v_final_grade >= 90 THEN v_letter_grade := 'A';
WHEN v_final_grade >= 80 THEN v_letter_grade := 'B';
WHEN v_final_grade >= 70 THEN v_letter_grade := 'C';
WHEN v_final_grade >= 60 THEN v_letter_grade := 'D';
ELSE v_letter_grade := 'F';
END CASE;
-- control resumes here after inner CASE terminates
DBMS_OUTPUT.PUT_LINE ('Letter grade is: '||v_letter_grade);
END CASE;
-- control resumes here after outer CASE terminates
END;
the above code I have taken from the book "Oracle PL/SQL by Example, 4th Edition 2009" my problem is when I enter a student_id not present in the table it returns me the following error
Error report: ORA-01403: no data found
ORA-06512: at line 7
01403. 00000 - "no data found"
*Cause:
*Action:
but according to the book it should have returned a null value and then follow the case flow.

Answer 1

When you are selecting INTO a variable and there are no records returned you should get a NO DATA FOUND error. I believe the correct way to write the above code would be to wrap the SELECT statement with it's own BEGIN/EXCEPTION/END block. Example:
...
v_final_grade NUMBER;
v_letter_grade CHAR(1);
BEGIN
BEGIN
SELECT final_grade
INTO v_final_grade
FROM enrollment
WHERE student_id = v_student_id
AND section_id = v_section_id;
EXCEPTION
WHEN NO_DATA_FOUND THEN
v_final_grade := NULL;
END;
CASE -- outer CASE
WHEN v_final_grade IS NULL THEN
...

Answer 2

There is an alternative approach I used when I couldn't rely on the EXCEPTION block at the bottom of my procedure. I had variables declared at the beginning:
my_value VARCHAR := 'default';
number_rows NUMBER := 0;
.
.
.
SELECT count(*) FROM TABLE INTO number_rows (etc.)
IF number_rows > 0 -- Then obtain my_value with a query or constant, etc.
END IF;

Answer 3

Might be worth checking online for the errata section for your book.
There's an example of handling this exception here http://www.dba-oracle.com/sf_ora_01403_no_data_found.htm

Answer 4

Your SELECT statement isn't finding the data you're looking for. That is, there is no record in the ENROLLMENT table with the given STUDENT_ID and SECTION_ID. You may want to try putting some DBMS_OUTPUT.PUT_LINE statements before you run the query, printing the values of v_student_id and v_section_id. They may not be containing what you expect them to contain.

Answer 5

This data not found causes because of some datatype we are using .
like select empid into v_test
above empid and v_test has to be number type , then only the data will be stored .
So keep track of the data type , when getting this error , may be this will help