Same results with cartesian product and JOIN

Question

What is the necessary condition to have the same result from a JOIN and a Cartesian Product ?

I don't think it is possible, if anyone can clear me will be great, thanks.I've searched but I couldn't an answer to my question.

score 1 · Accepted Answer · edited May 23 '17 at 12:12

If you are using SQL Server, the CROSS JOIN join type can achieve the same thing as a cartesian product. It matches every row from the left table to every row in the right. This is illustrated in the following SO question:

What is the difference between Cartesian product and cross join?

And a little MS documentation also: https://technet.microsoft.com/en-us/library/ms190690%28v=sql.105%29.aspx?f=255&MSPPError=-2147217396

score 1 · Answer 2 · answered Mar 04 '15 at 18:15

1

All three queries return the same result:

select *
from t1 cross join t2 

select *
from t1,t2 

select *
from t1 join t2 
on 1=1

answered Mar 04 '15 at 18:15

dnoeth

59,503
4
39
56

score 0 · Answer 3 · answered Mar 04 '15 at 18:15

0

A cartesian product is equivalent to a join that always evaluates to true. So

 Table1 join Table2 on 1=1

will give you a cartesian product.

answered Mar 04 '15 at 18:15

Matze

325
1
12

Same results with cartesian product and JOIN

3 Answers3