Using ACCEPT, CASE to create CURSOR in pl/sql - sql

Question

I am trying to create a script that will allow the user to select which CASE population to use from an ACCEPT when gathering student contact info.
PROMPT 'Select a popluation for emails'
PROMPT '1. Currently registered'
PROMPT '2. New Applicants'
PROMPT
ACCEPT cnt number PROMPT 'Selection: ';
...
CURSOR stu_lst IS
CASE &cnt
WHEN 1 THEN -- Current registered students.
select distinct SFRSTCA_PIDM pidm
from SFRSTCA
where SFRSTCA_TERM_CODE = '201403' and
SFRSTCA_LEVL_CODE = '01' and
SFRSTCA_RSTS_CODE = 'RE';
WHEN 2 THEN -- New applicants
select app_pidm pidm
from app
where app_term = 'Fall 2014';
ELSE
-- Incorrect selection.
DBMS_OUTPUT.PUT_LINE('Incorrect selection made.');
exit;
END;
END;

Answer 1

Assuming the two queries return the same data type, you could use a union with a filter that checks the variable in each part; something like:
DECLARE
CURSOR stu_lst IS
-- Current registered students.
select distinct SFRSTCA_PIDM pidm
from SFRSTCA
where &cnt = 1 and
SFRSTCA_TERM_CODE = '201403' and
SFRSTCA_LEVL_CODE = '01' and
SFRSTCA_RSTS_CODE = 'RE';
UNION ALL
-- New applicants
select app_pidm
from app
where &cnt = 2 and
app_term = 'Fall 2014';
invalid_argument EXCEPTION;
...
BEGIN
IF &cnt NOT IN (1, 2) THEN
RAISE invalid_argument;
END IF
FOR rec IN stu_lst LOOP
h_pidm := rec.pidm;
...
END LOOP;
EXCEPTION
WHEN invalid_argument THEN
dbms_output.put_line('Incorrect selection made.');
END;
/
You could also declare a cursor variable and open that with the appropriate query, inside a case statement within the main body of the block. This sticks with your explicit cursor syntax though.