SQLピボット例

Question

EAVモデル

create table people_details 
(id number 
, name varchar2(30) 
, det_number number 
, det_text varchar2(30) 
, prop_id number 
); 

create table properties 
(id number 
, description varchar2(30) 
); 

insert into properties values (1,'EYE COLOR'); 
insert into properties values (2,'INCOME'); 
insert into properties values (3,'EDUCATION'); 

INSERT INTO people_details VALUES (1,'JOHN',NULL,'BLUE',1); 
INSERT INTO people_details VALUES (2,'JOHN',5000,NULL,2); 
INSERT INTO people_details VALUES (3,'JOHN',NULL,'HIGHSCHOOL',3); 
INSERT INTO people_details VALUES (4,'PHILIP',NULL,'GREEN',1); 
INSERT INTO people_details VALUES (5,'PHILIP',7000,NULL,2); 
INSERT INTO people_details VALUES (6,'PHILIP',NULL,'COLLEGE',3); 
INSERT INTO people_details VALUES (7,'SANDY',NULL,'BROWN',1); 
INSERT INTO people_details VALUES (8,'SANDY',9000,NULL,2); 
INSERT INTO people_details VALUES (9,'SANDY',NULL,'COLLEGE',3); 

は今青い目または平均以上の収入を持つすべての人を選択します。 これは私が

WITH PEOPLE AS (
    SELECT * FROM(
    SELECT NAME, DESCRIPTION, NVL(DET_TEXT, TO_CHAR(DET_NUMBER)) AS DETAIL 
    FROM PEOPLE_DETAILS PPL 
    JOIN PROPERTIES PRO ON PPL.PROP_ID = PRO.ID 
) 
    PIVOT (
    MAX(DETAIL) 
    FOR DESCRIPTION IN ('EYE COLOR' as EYE_COLOR, 'EDUCATION' AS EDUCATION, 'INCOME' AS INCOME) 
) 
) 
SELECT * FROM PEOPLE WHERE EYE_COLOR = 'BLUE' 
UNION 
SELECT * FROM PEOPLE WHERE INCOME > (SELECT AVG(INCOME) FROM PEOPLE); 

やったことでこれを行うには、いくつかのよりよい方法はありますか？ここで私は収入を文字に変換し、平均関数はおそらく暗黙の変換を行います。プログラムで動作するかどうかは不明です。 これはどのように解決しますか？

Answer 1

私はgroup byとhavingを使用して、これを解決するだろう。このアプローチには

with p as (
     select pd.name, 
      max(case when p.description = 'EYE COLOR' then det_text end) as eye_color, 
      max(case when p.description = 'INCOME' then cast(det_text as number) end) as income, 
      max(case when p.description = 'EDUCATION' then det_text end) as education 
     from people_details pd join 
      properties p 
      on pd.prop_id = p.id 
     group by pd.name 
    ) 
select p.* 
from (select p.*, avg(income) over() as avg_income 
     from p 
    ) p 
where income > avg_income or eye_color = 'BLUE'; 

一つの利点をあなたはすぐにそれが計算された数値としてincomeを表現することができるということです。