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HetuEngine DQL SQL语法说明

MAPREDUCE服务 MRS-WITH

WITH WITH子句定义查询子句的命名关系，可以展平嵌套查询或简化子查询语句。例如下面的查询语句是等价的： SELECT name, maxprice FROM (SELECT name, MAX(price) AS maxprice FROM fruit GROUP BY name) AS x; WITH x AS (SELECT name, MAX(price) AS maxprice FROM fruit GROUP BY name) SELECT name, maxprice FROM x; 多个子查询 with t1 as(select name,max(price) as maxprice from fruit group by name), t2 as(select name,avg(price) as avgprice from fruit group by name) select t1.*,t2.* from t1 join t2 on t1.name = t2.name; WITH的链式形式 WITH x AS (SELECT a FROM t), y AS (SELECT a AS b FROM x), z AS (SELECT b AS c FROM y) SELECT c FROM z; 父主题： HetuEngine DQL SQL语法说明

MAPREDUCE服务 MRS HetuEngine DQL SQL语法说明