Besides INNER JOIN, HQL also supports regular OUTER JOIN and FULL JOIN. The logic of such a join is the same as what's in the SQL. The following table summarizes the differences between common joins. Here, we assume table_m has m rows and table_n has n rows with one-to-one mapping:
| Join type | Logic | Rows returned |
|
table_m JOIN table_n |
This returns all rows matched in both tables. | m ∩ n |
|
table_m LEFT JOIN table_n |
This returns all rows in the left table and matched rows in the right table. If there is no match in the right table, it returns NULL in the right table. | m |
|
table_m RIGHT JOIN table_n |
This returns all rows in the right table and matched rows in the left table. If there is no match in the left table, it returns ... |
