hive(讓我淩亂的一天)

子查詢有兩種一種是在from中
在from中相當於省去一張字段表

SELECT ... FROM(subquery)name...

SELECT col 
FROM (
 SELECT a+b AS col
FROM t1)

SELECT t3.ol
ROM (
SELECT a+b AS col
FROM t1
UNION ALL
SELECT c+d AS cal
FROM t2
) t3

另外一種是在where中操作
在where中的子查詢相當於條件單字段所以做不了多字段表(純屬個人理解)

SELECT *
FROM A
WHERE A.a IN (SELECT foo FROM B);

其他支持的types 有 EXISTS and NOT EXISTS
SELECT A
FROM T1
WHERE EXISTS(SELECT B FROM )
.....

最後更新：2017-10-27 00:03:28