Hive支持连接查询,但有一些条件必须遵守,比如只支持相等查询,其它查询如不等式查询则不支持,还支持外连接,左半连接查询。另外Hive支持多于两个表以上的连接查询。下面为Hive连接查询的语法:
join_table:
table_reference JOIN table_factor [join_condition]
| table_reference {LEFT|RIGHT|FULL} [OUTER] JOIN table_reference join_condition
| table_reference LEFT SEMI JOIN table_reference join_condition
| table_reference CROSS JOIN table_reference [join_condition] (as of Hive 0.10)
table_reference:
table_factor
| join_table
table_factor:
tbl_name [alias]
| table_subquery alias
| ( table_references )
join_condition:
ON equality_expression ( AND equality_expression )*
equality_expression:
expression = expression
上面的语法仅列出了连接查询的连接部分,至于查询部分可以