- A CROSS JOIN (also called a Cartesian Join) returns the Cartesian product of two tables.
- Every row from the first table is combined with every row from the second table
- No
ONcondition is used
- In the absence of a WHERE
condition the CARTESIAN JOIN will behave like a CARTESIAN PRODUCT . i.e., the
number of rows in the result-set is the product of the number of rows of the
two tables.
- In the presence of WHERE
condition this JOIN will function like a INNER JOIN.
- Generally speaking, Cross join is similar to an inner join where the join-condition will always evaluate to True.
SELECT * FROM TableA CROSS JOIN TableB;
or
SELECT * FROM TableA, TableB;
=============================================================================
| color |
|---|
| Red |
| Blue |
| size |
|---|
| Small |
| Large |
SELECT color, size FROM Colors CROSS JOIN Sizes;
| color | size |
|---|---|
| Red | Small |
| Red | Large |
| Blue | Small |
| Blue | Large |
Colors × Sizes = CROSS JOIN Output
-------- ------- ---------------------
Red Small → Red | Small
Red Large → Red | Large
Blue Small → Blue | Small
Blue Large → Blue | Large
=============================================================================
