Re: How do they get the answer?

From: Scott Shafer <sknd100_at_yahoo.com>
Date: Tue, 21 Aug 2001 13:41:19 -0700
Message-ID: <F001.00373027.20010821121342@fatcity.com>

Each subject has 2 teachers. By limiting the update by 2 subject_id's, you guarantee that 4 teachers will get a raise. Actually, this is poor SQL if a teacher teaches more than one subject (but that's not part of the problem).

Scott Shafer
San Antonio, TX

kjanusz_at_att.net wrote:
>
> I am taking the Self-Test software test for the SQL exam
> and don't see how they get the answer to this problem.
> They don't explain how it is arrived at.
>
> Any help you can give me will be appreciated.
>
> Thanks,
> Ken Janusz, CPIM
>
> ----------------------------------
>
> Examine the structure of the TEACHER table:
>
> Name Null? Type
> ID NOT NULL NUMBER(9)
> SALARY NUMBER
> (7,2)
> SUBJECT_ID NOT NULL NUMBER(3)
> SUBJECT_DESCRIPTION VARCHAR2(2)
>
> There are 200 teachers and 15 subjects. Each subject is
> taught
> by at least 2 teachers.
>
> Evaluate this PL/SQL block:
>
> DECLARE
> v_pct_raise number := 1.10;
> BEGIN
> UPDATE teacher
> SET salary = salary * 1.10
> WHERE subject_id IN (102, 105);
> COMMIT;
> END;
>
> Which result will the PL/SQL block provide?
>
> (A) Only two teachers will receive a 10% salary increase.
> (B) All of the teachers will receive a 10% salary
> increase.
> (C) At least four teachers will receive a 10% salary
> increase.
> (D) A syntax error will occur.
>
> Answer:
> (C)

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Author: Scott Shafer
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Received on Tue Aug 21 2001 - 15:41:19 CDT