Netezza中的子查询

Question

我正在尝试将SQL 11从Oracle 11 G移植到Netezza.

这是我在Oracle中的查询:

SELECT
    ID, TEACHERID, CLASS, SECTION, MAJOR, SUPERVISOR, COURSE, SCORE, SCOREDATE, 
    (select SCORE from STUDENT_SCORES d2 where d2.ID=d1.ID and d2.SCOREDATE (d1.SCOREDATE)-28 and d1.COURSE=d2.COURSE)  as PRIORSCORE, 
    (d1.SCOREDATE)-28 as PRIORSCOREDT,
    REMCD
FROM 
    STUDENT_SCORES d1
WHERE 
    TEACHERID='T1' AND SCOREDATE=(SELECT MAX(SCOREDATE) FROM STUDENT_SCORES WHERE TEACHERID='T1')

当我在Netezza中运行它时出现错误:

ERROR:  (2) This form of correlated query is not supported - consider rewriting

如何为Netezza重写此查询？请帮忙.

Answer 1

根据 Netezza文档

• UNION您不能在 SET 操作（ 、INTERSECT、EXCEPT和）中使用相关子查询MINUS。
• GROUP BY您不能在带有and子句的聚合中使用相关子查询HAVING。
• 不能在 ORed 子句或CASE/WHEN表达式中使用相关子查询。
• 您不能在列表中使用相关子查询IN。
• 您不能在列表中使用相关子查询SELECT。
  

重写的查询：（Oracle）（不确定Netezza语法）

SELECT
    d1.ID, d1.TEACHERID, d1.CLASS, d1.SECTION, d1.MAJOR, d1.SUPERVISOR, d1.COURSE, d1.SCORE, d1.SCOREDATE, 
    d2.SCORE as PRIORSCORE, 
    (d1.SCOREDATE)-28 as PRIORSCOREDT,
    d1.REMCD
FROM 
    STUDENT_SCORES d1
LEFT JOIN STUDENT_SCORES d2
ON (d2.ID=d1.ID and d2.SCOREDATE = (d1.SCOREDATE)-28 and d1.COURSE=d2.COURSE)
WHERE 
    d1.TEACHERID='T1' AND d1.SCOREDATE=(SELECT MAX(d3.SCOREDATE) FROM STUDENT_SCORES d3 WHERE d3.TEACHERID='T1')