# JOIN overview

`JOIN` combines rows from two or more tables. The examples below show matching rows and unmatched rows for the main join types.

## LEFT JOIN

| Query | Matching rows |
| --- | --- |
| `SELECT select_list FROM TableA A LEFT JOIN TableB B ON A.Key = B.Key` | ![LEFT JOIN](https://community-shared-data-1308875761.cos.ap-beijing.myqcloud.com/artwork/docs/reference/left_join.png) |
| `SELECT select_list FROM TableA A LEFT JOIN TableB B ON A.Key = B.Key WHERE B.Key IS NULL` | ![Unmatched left rows](https://community-shared-data-1308875761.cos.ap-beijing.myqcloud.com/artwork/docs/reference/left_join_where.png) |

## RIGHT JOIN

| Query | Matching rows |
| --- | --- |
| `SELECT select_list FROM TableA A RIGHT JOIN TableB B ON A.Key = B.Key` | ![RIGHT JOIN](https://community-shared-data-1308875761.cos.ap-beijing.myqcloud.com/artwork/docs/reference/right_join.png) |
| `SELECT select_list FROM TableA A RIGHT JOIN TableB B ON A.Key = B.Key WHERE A.Key IS NULL` | ![Unmatched right rows](https://community-shared-data-1308875761.cos.ap-beijing.myqcloud.com/artwork/docs/reference/right_join_where.png) |

## INNER JOIN

| Query | Matching rows |
| --- | --- |
| `SELECT select_list FROM TableA A INNER JOIN TableB B ON A.Key = B.Key` | ![INNER JOIN](https://community-shared-data-1308875761.cos.ap-beijing.myqcloud.com/artwork/docs/reference/inner_join.png) |

## FULL JOIN

| Query | Matching rows |
| --- | --- |
| `SELECT select_list FROM TableA A FULL OUTER JOIN TableB B ON A.Key = B.Key` | ![FULL JOIN](https://community-shared-data-1308875761.cos.ap-beijing.myqcloud.com/artwork/docs/reference/full_join.png) |
| `SELECT select_list FROM TableA A FULL OUTER JOIN TableB B ON A.Key = B.Key WHERE A.Key IS NULL OR B.Key IS NULL` | ![Unmatched rows from both tables](https://community-shared-data-1308875761.cos.ap-beijing.myqcloud.com/artwork/docs/reference/full_join_where.png) |

## Related references

- [LEFT JOIN](left-join.md)
- [RIGHT JOIN](right-join.md)
- [INNER JOIN](inner-join.md)
- [FULL JOIN](full-join.md)
- [OUTER JOIN](outer-join.md)
- [NATURAL JOIN](natural-join.md)