SQL CROSS JOIN question

Question

I am having a bit of trouble with my SQL query.

I have two tables:

Table1

id  guid  title     D0      D1     D2
-----------------------------------------
1   guid1 Title1    0.123  -0.235  0.789
2   guid2 Title2   -0.343   0.435  0.459
3   guid3 Title3    0.243  -0.267 -0.934
...
100 guid4 Title100 -0.423   0.955  0.029

and Table 2 (note it has the same schema, just different data).

id  guid  title     D0      D1     D2
----------------------------------------
1   guid1 Title1    0.233  -0.436 -0.389
2   guid2 Title2   -0.343   0.235  0.789
3   guid3 Title3    0.573  -0.067 -0.124
...
100 guid4 Title100 -0.343   0.155  0.005

I am trying to figure out how to write a SELECT statement which returns all the titles WHERE all the combinations of ABS(Table1_D0*Table2_D0)+ABS(Table1_D1*Table2_D1)+ABS(Table1_D2*Table2_D2) are less than a thresholded value (hard coded probably).

So far I am trying to use a CROSS JOIN , but I am not sure if this is the correct approach.

Does this make sense? Table1, row1 against all the rows of Table2 , then Table1, row2 against all the rows of Table2 .

If it matters, I am using MS SQL.

Many thanks! Brett

Answer 1

SELECT t1.title
FROM Table1 t1
CROSS JOIN table2 t2
WHERE ABS(t1.D0*t2.D0)+ABS(t1.D1*t2.D1)+ABS(t1.D2*t2.D2)<10

Answer 2

CROSS JOIN是正确的选择，而CROSS JOIN则与根本没有联接一样（请参见Snowbear答案）。

Answer 3

SELECT *
  FROM  Table1 a inner join
        Table2 b on a.Id=b.Id
where   ABS(a.D0*b.D0)+ABS(a.D1*b.D1)+ABS(a.D2*b.D2)<=@Value

Answer 4

select t1o.title
from Table1 t1o
where not exists
(
    -- none of the cross-joined rows for t1o must be above the threshold
    select t1.title
    from Table1 t1
    cross join Table2 t2
    where t1.id = t1o.id -- only the cross joined rows for the current t1o row
    -- inverted b/c not exists
    and abs(t1.D0*t2.D0)+abs(t1.D1*t2.D1)+abs(t1.D2*t2.D2) > 10 
)