功能:将两个表中的 同样的字段拼接到一起
測试:
create external table IF NOT EXISTS temp_uniontest_ta ( a1 string, a2 string ) partitioned by (dt string) row format delimited fields terminated by '\t' stored as textfile; ALTER TABLE temp_uniontest_ta ADD IF NOT EXISTS PARTITION (dt = '2014-10-13') location '/temp/unionTest/ta/'; a1 a2 2014-10-13 b1 b2 2014-10-13 c1 c2 2014-10-13 create external table IF NOT EXISTS temp_uniontest_tb ( a1 string, a2 string ) partitioned by (dt string) row format delimited fields terminated by '\t' stored as textfile; ALTER TABLE temp_uniontest_tb ADD IF NOT EXISTS PARTITION (dt = '2014-10-13') location '/temp/unionTest/tb/'; d1 d2 2014-10-13 e1 e2 2014-10-13 select * from ( select a1,a2 from temp_uniontest_ta where dt = '2014-10-13' union all select a1,a2 from temp_uniontest_tb where dt = '2014-10-13' )tmp; a1 a2 b1 b2 c1 c2 d1 d2 e1 e2