Hive支持的表连接查询的语法：
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只支持等连接，外连接，左半连接。hive不支持非相等的join条件（可以通过其他方式实现），因为它很难在map/reduce job实现这样的条件。而且，hive可以join两个以上的表。
原文：https://www.cnblogs.com/shujuxiong/p/9718913.html