SQL-查詢加入3個表，按特定列分組並按年份過濾？

Question

問題：

按 state 細分的 2019 年收購的物業在 2020 年的總分配是多少？

到目前為止，這就是我所擁有的，似乎我沒有得到正確的總結？ 我錯過了什么步驟。 我沒有收到錯誤但也沒有得到答案？ 有任何想法嗎？

CREATE TABLE Property
(
    hmy INT   NOT NULL,
    scode VARCHAR   NOT NULL,
    saddr1 VARCHAR NOT NULL,
    saddr2 VARCHAR NOT NULL,
    scity VARCHAR NOT NULL,
    sstate VARCHAR NOT NULL,
    szipcode INT NOT NULL,
    PRIMARY KEY (hmy) 
);

CREATE TABLE PropInfo
(
    hmy INT   NOT NULL,
    hcode INT   NOT NULL,
    acquisitiondate DATE   NOT NULL,
    unitcount INT   NOT NULL,
    yearbuilt INT   NOT NULL,
    distributionentitycode VARCHAR   NOT NULL,
    PRIMARY KEY (hcode)
);

CREATE TABLE DistributionLog
(
    hmy INT   NOT NULL,
    hcode INT   NOT NULL,
    distributionDate DATE   NOT NULL,
    distributiontype VARCHAR   NOT NULL,
    distributionamount INT   NOT NULL,
    PRIMARY KEY (hmy)
);

SELECT SUM(DL.distributionamount) AS Total, PY.sstate, PI.acquisitiondate, DL.distributionamount 
FROM DistributionLog AS DL
JOIN PropInfo AS PI
ON PI.hmy = DL.hcode
JOIN Property AS PY
ON PY.hmy = PI.hmy
WHERE distributionDate BETWEEN '2020-1-1' AND '2020-12-31'
GROUP BY PY.sstate, PI.acquisitiondate, DL.distributionamount
ORDER BY PY.sstate;

這是嘗試過的：

Answer 1

你可以嘗試這樣的事情：

select p.sstate, sum(distributionamount)
from distributionlog d
inner join propinfo pi
  on d.hcode = pi.hcode
  and extract(year from acquisitiondate) = 2019
  and extract(year from distributiondate) = 2020
inner join property p on pi.hmy = p.hmy
group by p.sstate

在這個 SQL 中，我們將加入 3 個表格，就像您一直在做的那樣。 我們在加入期間指定，以確保收購日期應在 2019 年，分發日期應從 2020 年開始。

Answer 2

由於您想要sum(DL.distributionamount) ，因此 DL.distributionamount不應在 group by 子句中。 下面的查詢應該返回您在 2019 年獲得並在 2020 年分發的屬性的狀態明智總和（DL.distributionamount）。（沒有樣本數據，我不清楚表之間的關系。所以我假設你做了加入權)

SELECT  PY.sstate, SUM(DL.distributionamount) AS Total
FROM DistributionLog AS DL
JOIN PropInfo AS PI
ON PI.hmy = DL.hcode and PI.acquisitiondate BETWEEN '2019-1-1' AND '2019-12-31'
JOIN Property AS PY
ON PY.hmy = PI.hmy
WHERE distributionDate BETWEEN '2020-1-1' AND '2020-12-31'
GROUP BY PY.sstate
ORDER BY PY.sstate;