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Example
Data
The data below is used in the explicit and implicit example
table1 (inner set) | table2 (outer set) |
|
---|---|---|
Column ID | Column ID | Column ID_2 |
A | A | |
B | B | A |
D | C | C |
And we want:
ID_table1 ID_table2
---------- ----------
A A
A B
A C
B A
B B
B C
D A
D B
D C
9 rows selected.
We have 3 rows from table1 to multiply by 3 rows in the table2.
Real example of cross-join in this article : OWB - How to load a fact table for a data quality cube ?
Explicit
SELECT
table1.id "ID_table1"
, table2.id "ID_table2"
FROM
table1
CROSS JOIN table2;
Implicit
- There is no join condition
select table1.id "ID_table1", table2.id "ID_table2"
from table1, table2
- in case of when the application controls that you have set a join condition, you can add the 1=1 predicate.
select table1.id "ID_table1", table2.id "ID_table2"
from table1, table2
where 1=1;