SQL Server 2019

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CREATE TABLE PLANCOURSES ([EMPLID] int, [ID] int, [QTR] int, [SUBJ] varchar(7), [COURSE_NUM] int);
INSERT INTO PLANCOURSES
    ([EMPLID], [ID], [QTR], [SUBJ], [COURSE_NUM])
VALUES
    (11111, 1, 2213, 'HCML', 325),
    (11111, 1, 2213, 'HPM', 340),
    (11111, 1, 2215, 'CMST', 330),
    (22222, 1, 2213, 'ART', 110),
    (22222, 1, 2213, 'GENERAL', 1),
    (22222, 1, 2213, 'GENERAL', 5),
    (33333, 1, 2213, 'GENERAL', 5);

CREATE TABLE COURSEWORK ([EMPLID] int, [QTR] int, [SUBJ] varchar(5), [COURSE_NUM] int);
INSERT INTO COURSEWORK
    ([EMPLID], [QTR], [SUBJ], [COURSE_NUM])
VALUES
    (11111, 2213, 'CMST', 330),
    (11111, 2213, 'HCML', 325),
    (11111, 2215, 'HPM', 340),
    (22222, 2213, 'ART', 105),
    (22222, 2213, 'ENGL', 201),
    (22222, 2213, 'ASTR&', 101),
    (33333, 2213, 'ASTR&', 101),
    (33333, 2213, 'BIOL', 108);

CREATE TABLE GENERAL ([SUBJ] varchar(5), [NUM] int, [MAPPING] int);
INSERT INTO GENERAL
    ([SUBJ], [NUM], [MAPPING])
VALUES
    ('ENGL&', 101, 1),
    ('ENGL', 201, 1),
    ('ENGL&', 235, 1),
    ('ANTH&', 215, 5),
    ('ASTR&', 101, 5),
    ('BIOL', 108, 5);
21 rows affected

select *,
    case when r.COURSE_NUM is null then 'MISMATCH' else 'MATCH' end as FOLLOW_PLAN
from
    PLANCOURSES e
    left outer join GENERAL g
        on e.SUBJ = 'GENERAL' and g.MAPPING = e.COURSE_NUM
    left outer join COURSEWORK r    
        on  r.EMPLID = e.EMPLID and r.QTR = e.QTR 
            and (
                    e.SUBJ <> 'GENERAL' and r.SUBJ = e.SUBJ and r.COURSE_NUM = e.COURSE_NUM
                or  e.SUBJ  = 'GENERAL' and r.SUBJ = g.SUBJ and r.COURSE_NUM = g.NUM
            )
            /* equivalently
            -- order matters inside the coalesce()
            and r.SUBJ       = COALESCE(g.SUBJ, e.SUBJ)
            and r.COURSE_NUM = COALESCE(g.NUM,  e.COURSE_NUM)
            */
where e.EMPLID <> 33333
    and     (g.NUM is null      or r.COURSE_NUM is not null)
    and not (g.NUM is not null and r.COURSE_NUM is null)


EMPLID
ID
QTR
SUBJ
COURSE_NUM
SUBJ
NUM
MAPPING
EMPLID
QTR
SUBJ
COURSE_NUM
FOLLOW_PLAN


11111
1
2213
HCML
325
null
null
null
11111
2213
HCML
325
MATCH

11111
1
2213
HPM
340
null
null
null
null
null
null
null
MISMATCH

11111
1
2215
CMST
330
null
null
null
null
null
null
null
MISMATCH

22222
1
2213
ART
110
null
null
null
null
null
null
null
MISMATCH

22222
1
2213
GENERAL
1
ENGL
201
1
22222
2213
ENGL
201
MATCH

22222
1
2213
GENERAL
5
ASTR&
101
5
22222
2213
ASTR&
101
MATCH


-- EMPLID 33333 will match to two completed courses against one general plan course
select
    e.EMPLID, e.ID, e.QTR, e.SUBJ, e.COURSE_NUM,
    coalesce(r.SUBJ, g.SUBJ) as MATCHED_SUBJ,
    coalesce(r.COURSE_NUM, g.NUM) as MATCHED_COURSE_NUM,
    case when r.COURSE_NUM is null then 'MISMATCH' else 'MATCH' end as FOLLOW_PLAN,
    case when e.SUBJ = 'GENERAL' and count(*) over (partition by e.EMPLID, e.QTR, e.COURSE_NUM) > 1 then
        '*' else '' end as MultiMatch
from
    PLANCOURSES e
    left outer join GENERAL g
        on e.SUBJ = 'GENERAL' and g.MAPPING = e.COURSE_NUM
    left outer join COURSEWORK r    
        on  r.EMPLID = e.EMPLID and r.QTR = e.QTR 
            and (
                    e.SUBJ <> 'GENERAL' and r.SUBJ = e.SUBJ and r.COURSE_NUM = e.COURSE_NUM
                or  e.SUBJ  = 'GENERAL' and r.SUBJ = g.SUBJ and r.COURSE_NUM = g.NUM
            )
where (g.NUM is null or r.COURSE_NUM is not null);
            


EMPLID
ID
QTR
SUBJ
COURSE_NUM
MATCHED_SUBJ
MATCHED_COURSE_NUM
FOLLOW_PLAN
MultiMatch


11111
1
2213
HCML
325
HCML
325
MATCH


11111
1
2213
HPM
340
null
null
MISMATCH


11111
1
2215
CMST
330
null
null
MISMATCH


22222
1
2213
GENERAL
1
ENGL
201
MATCH


22222
1
2213
GENERAL
5
ASTR&
101
MATCH


22222
1
2213
ART
110
null
null
MISMATCH


33333
1
2213
GENERAL
5
ASTR&
101
MATCH
*

33333
1
2213
GENERAL
5
BIOL
108
MATCH
*

EMPLID	ID	QTR	SUBJ	COURSE_NUM	SUBJ	NUM	MAPPING	EMPLID	QTR	SUBJ	COURSE_NUM	FOLLOW_PLAN
11111	1	2213	HCML	325	null	null	null	11111	2213	HCML	325	MATCH
11111	1	2213	HPM	340	null	null	null	null	null	null	null	MISMATCH
11111	1	2215	CMST	330	null	null	null	null	null	null	null	MISMATCH
22222	1	2213	ART	110	null	null	null	null	null	null	null	MISMATCH
22222	1	2213	GENERAL	1	ENGL	201	1	22222	2213	ENGL	201	MATCH
22222	1	2213	GENERAL	5	ASTR&	101	5	22222	2213	ASTR&	101	MATCH