Error user input PLS-00201: identifier 'ISS' must be declared [duplicate] - oracle

Question

This question already has an answer here:
PLS-00201: identifier 'USER INPUT' must be declared
(1 answer)
Closed 10 months ago.
Why do I get this error? If the variable declaration is the same type as the column shouldn't this work. The nursing_unit_id is a varchar2(10). It worked like this for me when the ID was a NUMBER;
Error I get:
Error report -
ORA-06550: line 13, column 13:
PLS-00201: identifier 'ISS' must be declared
SET SERVEROUTPUT ON;
DECLARE
v_unit ADMISSIONS.NURSING_UNIT_ID%TYPE := &v_unit;
v_admissions ADMISSIONS%ROWTYPE;
CURSOR c_admissions IS
SELECT *
INTO v_admissions
FROM ADMISSIONS
WHERE NURSING_UNIT_ID = v_unit;
BEGIN
FOR r_admissions IN c_admissions
LOOP
DBMS_OUTPUT.PUT_LINE(r_admissions );
END LOOP;
END;

Answer 1

If nursing_unit_id is varchar2(10) and you've defined the substitution variable &v_unit as ISS, then you have to enclose the reference to the substitution variable in quotes, to make it a string:
v_unit ADMISSIONS.NURSING_UNIT_ID%TYPE := '&v_unit';
If you run your code in SQL*Plus or SQL Developer with set verify on, you'll see the before and after values for that substitution, which would show it it trying to to do:
v_unit ADMISSIONS.NURSING_UNIT_ID%TYPE := ISS;
instead of what you'd get with it quoted:
v_unit ADMISSIONS.NURSING_UNIT_ID%TYPE := 'ISS';
You will still get other errors; the next one is:
PLS-00306: wrong number or types of arguments in call to 'PUT_LINE'
You've defined v_admissions as a row type, which means it's a record. You can't write a whole record out in one go with dbms_output, you have to refer to each field separately, e.g. (using your amended code, where `r_admissions is also implicitly of that same row type):
DBMS_OUTPUT.PUT_LINE(r_admissions.nursing_unit_id);
Having an into clause in the cursor definition isn't useful; it isn't actually populated, so you can remove that clause and the v_admissions variable declaration. You don't really need the v_unit local variable either, you can use the substitution variable directly; and there are various cursor forms you can use, such as:
SET SERVEROUTPUT ON;
BEGIN
FOR r_admissions IN (
SELECT *
FROM ADMISSIONS
WHERE NURSING_UNIT_ID = '&v_unit'
)
LOOP
DBMS_OUTPUT.PUT_LINE(r_admissions.nursing_unit_id);
-- and anything else you want to do with that row's data
END LOOP;
END;
/