Hive支持的表連接查詢的語法：

 1     join_table:  
 2         table_reference JOIN table_factor [join_condition]  
 3       | table_reference {LEFT|RIGHT|FULL} [OUTER] JOIN table_reference join_condition  
 4       | table_reference LEFT SEMI JOIN table_reference join_condition  
 5       | table_reference CROSS
 
 JOIN table_reference [join_condition] (as of Hive 0.10)  
 6       
 7     table_reference:  
 8         table_factor  
 9       | join_table  
10       
11     table_factor:  
12         tbl_name [alias]  
13       | table_subquery alias  
14       | ( table_references )  
15       
16     join_condition:  
 
17         ON equality_expression ( AND equality_expression )*  
18       
19     equality_expression:  
20         expression = expression 

hive只支持等連接，外連接，左半連接。hive不支持非相等的join條件（可以通過其他方式實現），因為它很難在map/reduce job實現這樣的條件。而且，hive可以join兩個以上的表。

Hive的join表連接查詢的一些註意事項