I have a problem to solve;
I have a stock of postage stamps of four different denominations - 1p, 5p, 19p and 27p
Postage is charged in bands:
Second class postage for an item weighing >150g<200g is 54p - the most efficient way to make this up is to use 2x27p stamps
First class postage for the same item costs 72p; one way to make this up would be 1x27p + 2x19p + 1x5p + 2x1p (6 stamps in 4 denominations), but another would be 3x19p + 3x5p (6 stamps in 2 denominations), yet another would be 2x27p + 3x5p + 3x1p (7 stamps in 3 denominations.
Efficiency is here defined as the firstly the least number of stamps and if there is more than one possible solution, the least number of denominations, so the 6 stamps in 2 demoninations solution appears to be the best.
Anyway, I know how I will do it, but I want to know if the SQL I intend to use is non-standard or frowned upon in some way.
Suppose I have two tables:
Table1:
Num
1
2
3
Table2:
Alph
A
B
C
(Using Jet SQL in Microsoft Access), this query:
SELECT Table1.Num, Table2.Alph
FROM Table1, Table2;
Yields the desired result of every possible combination of the two:
Num, Alph
1,A
2,A
3,A
1,B
2,B
3,B
1,C
2,C
3,C
It does so because there is no join specified.
Is this a quirk of Jet SQL (or a quirk of SQL generally), or is it a documented and approved technique? i.e. Am I going to find that an attempt to implement similar techniques on other DB apps fails miserably?