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
  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);

CREATE TABLE CourseWork(
  EMPLID int
  ,QTR int
  ,SUBJ varchar(7)
  ,COURSE_NUM int
  );
  
INSERT INTO CourseWork
  VALUES
  (11111,2213,'CMST',330)
  ,(11111,2213,'HCML',325)
  ,(11111,2215,'HPM',340)
  ,(22222,2213,'ART',110)
  ,(22222,2213,'ENGL',201)
  ,(22222,2213,'ASTR&',101);

CREATE TABLE PlaceholderCourse (
  SUBJ varchar(7)
  ,NUM int
  ,MAPPING int);
  
INSERT INTO PlaceholderCourse
  VALUES
  ('ENGL&',101,1)
  ,('ENGL',201,1)
  ,('ENGL&',235,1)
  ,('ANTH&',215,5)
  ,('ASTR&',101,5)
  ,('BIOL',108,5);
18 rows affected

SELECT * FROM PlanCourses;
SELECT * FROM CourseWork;
SELECT * FROM PlaceholderCourse;


EMPLID
ID
QTR
SUBJ
COURSE_NUM


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




EMPLID
QTR
SUBJ
COURSE_NUM


11111
2213
CMST
330

11111
2213
HCML
325

11111
2215
HPM
340

22222
2213
ART
110

22222
2213
ENGL
201

22222
2213
ASTR&
101




SUBJ
NUM
MAPPING


ENGL&
101
1

ENGL
201
1

ENGL&
235
1

ANTH&
215
5

ASTR&
101
5

BIOL
108
5


SELECT
    E.EMPLID
    ,E.ID
    ,E.QTR
    ,E.SUBJ
    ,E.COURSE_NUM
    ,R.SUBJ
    ,R.COURSE_NUM
    ,CASE 
        WHEN E.SUBJ = 'GENERAL'
        THEN 'PLACEHOLDER'
        WHEN R.SUBJ IS NOT NULL
        THEN 'Match'
        ELSE 'Mismatch'
        END AS FOLLOW_PLAN
    
FROM 
    PLANCOURSES E

    LEFT JOIN COURSEWORK R 
        ON R.EMPLID = E.EMPLID
        AND R.QTR = E.QTR
        AND R.SUBJ = E.SUBJ
        AND R.COURSE_NUM = E.COURSE_NUM


EMPLID
ID
QTR
SUBJ
COURSE_NUM
SUBJ
COURSE_NUM
FOLLOW_PLAN


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
ART
110
ART
110
Match

22222
1
2213
GENERAL
1
null
null
PLACEHOLDER

22222
1
2213
GENERAL
5
null
null
PLACEHOLDER
EMPLID	ID	QTR	SUBJ	COURSE_NUM
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