theorem_hunter

May 4th, 2007, 09:10 PM

i just need something cleared up here...

i am studying for a discrete maths test, inclusion-exclusion principles is on of the topics being covered, and i was wondering if that is the same principle for SQL statements.

inclusion-exclusion - here is 1 part of a question:

In a class of 200 students 75 take maths, 70 take stats & 75 take zoology.

35 take maths & zoology

20 take stats & zoology

40 take maths & stats

15 take all 3 subjects

so this becomes...

|U| = 200

|M| = 75

|S| = 70

|Z| = 75

|M∩Z| = 35

|S∩Z| = 20

|M∩S| = 40

|M∩S∩Z| = 15

Q. How many take at least 1 of the 3 subjects?

A.

|M∪S∪Z| = |M| + |S| + |Z| - |M∩S| - |M∩Z| - |S∩Z| + |M∩S∩Z|

= 75 + 70 + 75 - 40 - 35 - 20 + 15

= 140

140 students take at least 1 of the 3 subjects

sql - this is not a working sql statement... im just trying to show/understand the concept.

my question...

could a sql statement for the above maths statement look like this? or what would the sql statement look like?

select *

from U

where ((M + S + Z) - ((M+S)-(M+Z)-(S+Z)) + (M+S+Z) <= U)

do sql select-from-where statements use inclusion exclusion principles to get their answers? thanks

i am studying for a discrete maths test, inclusion-exclusion principles is on of the topics being covered, and i was wondering if that is the same principle for SQL statements.

inclusion-exclusion - here is 1 part of a question:

In a class of 200 students 75 take maths, 70 take stats & 75 take zoology.

35 take maths & zoology

20 take stats & zoology

40 take maths & stats

15 take all 3 subjects

so this becomes...

|U| = 200

|M| = 75

|S| = 70

|Z| = 75

|M∩Z| = 35

|S∩Z| = 20

|M∩S| = 40

|M∩S∩Z| = 15

Q. How many take at least 1 of the 3 subjects?

A.

|M∪S∪Z| = |M| + |S| + |Z| - |M∩S| - |M∩Z| - |S∩Z| + |M∩S∩Z|

= 75 + 70 + 75 - 40 - 35 - 20 + 15

= 140

140 students take at least 1 of the 3 subjects

sql - this is not a working sql statement... im just trying to show/understand the concept.

my question...

could a sql statement for the above maths statement look like this? or what would the sql statement look like?

select *

from U

where ((M + S + Z) - ((M+S)-(M+Z)-(S+Z)) + (M+S+Z) <= U)

do sql select-from-where statements use inclusion exclusion principles to get their answers? thanks