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MySQL query Syntax with many to many relationship...

Posted on 2009-04-13
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Last Modified: 2012-05-06
I have a table employees and a table shifts.  They have a many to many relationship.

I want to be able to view the employees who are logged into two/three specific shifts.
So the query is kinda like this...

SELECT SHIFTS.EMP_ID,
      SHIFTS.SHIFT_ID,
      EMPLOYEES.EMP_FNAME
FROM EMPLOYEES INNER JOIN SHIFTS ON EMPLOYEES.EMP_ID = SHIFTS.EMP_ID
WHERE SHIFT_ID = (26 AND 27 AND 28)

except the where statement is clearly wrong.  I want it to return the employees who are logged onto the shifts 26 AND 27 AND 28.

Please help with the syntax.  Thanks in advance!
Nick
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Question by:Chimeraza
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4 Comments
 
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Expert Comment

by:racek
ID: 24128788
SELECT SHIFTS.EMP_ID,
      SHIFTS.SHIFT_ID,
      EMPLOYEES.EMP_FNAME, count(distinct SHIFT_ID) shifts
FROM EMPLOYEES
JOIN SHIFTS ON EMPLOYEES.EMP_ID = SHIFTS.EMP_ID
WHERE SHIFT_ID IN (26 ,27 ,28)
group by 1,2,3
HAVING count = 3;
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LVL 14

Expert Comment

by:racek
ID: 24128791
oops

SELECT SHIFTS.EMP_ID,
      SHIFTS.SHIFT_ID,
      EMPLOYEES.EMP_FNAME, count(distinct SHIFT_ID) shifts
FROM EMPLOYEES
JOIN SHIFTS ON EMPLOYEES.EMP_ID = SHIFTS.EMP_ID
WHERE SHIFT_ID IN (26 ,27 ,28)
group by 1,2,3
HAVING shifts = 3;
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Accepted Solution

by:
racek earned 500 total points
ID: 24128804
or more info:
SELECT SHIFTS.EMP_ID,
      SHIFTS.SHIFT_ID,
      EMPLOYEES.EMP_FNAME,
      count(distinct IF(SHIFT_ID IN (26 ,27 ,28),SHIFT_ID, NULL)) shifts,
      COUNT( distinct SHIFT_ID) total_shifts
FROM EMPLOYEES
JOIN SHIFTS ON EMPLOYEES.EMP_ID = SHIFTS.EMP_ID
group by 1,2,3
HAVING shifts = 3;

if SHIFTS has UNIQUE EMP_ID + SHIFT_ID, you can remove DISTINCT from count
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LVL 3

Author Closing Comment

by:Chimeraza
ID: 31569439
Thanks, works like a charm!
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