SQL Invalid Identifier when using bind variable - sql

Question

Using my anonymous block I have written below, the bind variable is giving me the error: I've pasted a picture of the table below.
edit: ETHI1022 is the input I'm giving for the CORID
v_corid CHAR(8) := ETHI1022;
*
ERROR at line 3:
ORA-06550: line 3, column 24:
PLS-00201: identifier 'ETHI1022' must be declared
ORA-06550: line 0, column 0:
PL/SQL: Compilation unit analysis terminated
I realize my inner join is most likely messed up like no other. I'm trying to learn this stuff and am having a very hard time learning how taking values from the select statement and placing them into the variables in the declare section works.
DECLARE
v_marstuid MARKS.STUID%TYPE;
v_corid CHAR(8) := &corid;
v_avgmark NUMBER(2);
v_maxmark NUMBER(2);
v_minmark NUMBER(2);
v_cordesc VARCHAR2(255);
ex_CourseNotFound EXCEPTION;
BEGIN
SELECT Count(M.stuid),
M.corid,
Avg(M.mark),
Max(M.mark),
Min(M.mark),
C.descript
INTO v_marstuid, v_corid, v_avgmark, v_maxmark,
v_minmark, v_cordesc
FROM marks M
inner join courses C
ON M.corid = C.corid
WHERE C.corid = v_corid;
dbms_output.Put_line (v_corid
|| ' - '
|| v_cordesc);
dbms_output.Put_line ('Course Stats: ');
dbms_output.Put_line ('Number of students: '
|| v_marstuid);
dbms_output.Put_line ('Average: '
|| v_avgmark);
dbms_output.Put_line ('Marks Range: ');
dbms_output.Put_line ('High: '
|| v_maxmark);
dbms_output.Put_line ('Low: '
|| v_minmark);
EXCEPTION
WHEN ex_CourseNotFound THEN
DBMS_OUTPUT.PUT_LINE(v_corcode || ' Does not exist.');
END;
/
[Table used]

Answer 1

Instead of ETHI1022 it should be 'ETHI1022'. Your inner join is fine. From where you are getting value of corid. Make it of type varchar/string or something like that.
Or you might try v_corid CHAR(8) := ''''||&corid||'''';