SQL fundamentals I exam guide - (mod(employee_id,4)+1) mistake?

Question

Hi guys, am getting a bit fed up with the official SQL I exam to be honest. I think I've found another mistake......
On page 341 it has this example:
+"You wish to divide staff into four groups named after the four regions in the REGIONS table. Is it possible to obtain a list of EMPLOYEE_ID, LAST_NAME, and REGION_NAME values for each employee by joining the EMPLOYEE_ID and REGION_ID columns in a round-robin manner?+
+Yes. The REGION_ID value ranges from 1 to 4. Adding 1 to the remainder of EMPLOYEE_ID divided by 4 creates a value in the range 1 to 4. The round-robin assignment of employees may be done as+
+follows:+
*SELECT LAST_NAME, EMPLOYEE_ID, REGION_NAME,*
*FROM EMPLOYEES*
*JOIN REGIONS ON (MOD(EMPLOYEE_ID,4)+1=REGION_ID)*"
BUT THIS APPEARS TO JUST BE WRONG (syntax errors aside)
Prior to reading the answer I wrote the following solution (which appears to produce the correct answers):
SELECT e.last_name, e.employee_id, r.region_name
from employee e
full outer join departments d on (e.department_id=d.department_id)
full outer join locations l on (d.location_id=l.location_id)
full outer join countries c on (l.country_id=c.country_id)
full outer join regions r on (c.region_id=r.region_id)
order by r.region_id;
I've checked the results individually, (and added the code (mod(employee_id,4)+1) to my select statement for comparison) and the exam guide just appears to be wrong (it assigns for example employee Zlotkey 179 to region 2, rather than region 1, which is Europe)
Am I missing something?????!!!!!!
Thanks,
Nick

Answer 1

Hi, Nick
You found the correct answer for a different question.
The question was:
nick woodward wrote:
... On page 341 it has this example:
+"You wish to divide staff into four groups named after the four regions in the REGIONS table. Is it possible to obtain a list of EMPLOYEE_ID, LAST_NAME, and REGION_NAME values for each employee by joining the EMPLOYEE_ID and REGION_ID columns in a round-robin manner?+This seems to be asking you to assign each employee to a region arbitrarily. It does not assume that there is any actual relationship between employees and regions.
>
+Yes. The REGION_ID value ranges from 1 to 4. Adding 1 to the remainder of EMPLOYEE_ID divided by 4 creates a value in the range 1 to 4. The round-robin assignment of employees may be done as+
+follows:+
*SELECT LAST_NAME, EMPLOYEE_ID, REGION_NAME,*
*FROM EMPLOYEES*
*JOIN REGIONS ON (MOD(EMPLOYEE_ID,4)+1=REGION_ID)*"
BUT THIS APPEARS TO JUST BE WRONG (syntax errors aside)Do you mean "syntax error [singular] aside"?
The only error I see is the comma at the end of the SELECT clause. They did, however, spell employees correctly, so they had the same number of errors as you.
I agree that this is a confusing question, partly because the question it addresses is something that occurs so rarely in real life. It's a shame they couldn't think of a better question, or a better way of phrasing this one.
Edited by: Frank Kulash on Apr 8, 2013 4:40 PM