如何将此相关子查询转换为 Vertica 友好的非相关查询

Question

我有以下 SQL 服务器查询，需要将其转换为 Vertica 查询。现在的问题是 vertica 不支持多级相关子查询，所以在我的示例中 t3.a = t1.a 不起作用

select * from t1
    where not exists (
      select * from t2
      where t2.y = t1.y 
      and t2.x in (
          select top 1 x from t3
          where t3.z = t2.z
          and t3.a = t1.a
          order by t3.b
          )
     )

谁能帮我做这个？

Answer 1

Vertica 不支持超过 1 级的相关子查询，您应该将它们转换为 JOIN。

它也不支持 TOP x 子句，请改用 LIMIT x。

像这样：

SELECT t1.*
FROM t1
LEFT JOIN t2 ON t1.y = t2.y
WHERE t2.y IS NULL
  AND t2.x IN
    (SELECT t3.x
     FROM t3
     JOIN t2 ON t3.z = t2.z
     JOIN t1 ON t3.a=t1.a
     ORDER BY t3.b LIMIT 1);

如何将此相关子查询转换为 Vertica 友好的非相关查询

How to convert this correlated sub query to Vertica friendly non correlated query

vertica