kunHøyreRightJoin

                venstre høyre  kunHøyreRightJoin
2020-01-01 +---+
| x |
2020-01-02 | | +---+ +------------+
| | | 1 | | 1 |
2020-01-03 +---+ | | +------------+
| | | 1 |
2020-01-04 +---+ +------------+

2020-01-05 +---+
| y |
2020-01-06 +---+