Question

我的数据库中有地址和定价数据。定价数据不完整，通常适用于某个地区，其他时间适用于特定地址。我有一个plpgsql函数，可以检索最准确的定价数据。我目前在我的功能中有这个：

SELECT price_est.sau_price_avg INTO _est_price FROM price_est WHERE price_est.neighbourhood_id = _neighbourhood_id AND  --neighbourhood level
                                                                    price_est.district_id = _district_id AND
                                                                    price_est.municipality_id = _municipality_id AND
                                                                    price_est.county_id = _county_id;
IF _est_price IS NULL THEN
    SELECT price_est.sau_price_avg INTO _est_price FROM price_est WHERE price_est.neighbourhood_id IS NULL AND          --district level
                                                                        price_est.district_id = _district_id AND
                                                                        price_est.municipality_id = _municipality_id AND
                                                                        price_est.county_id = _county_id;
END IF;
...

如果某处的数据不可用，则该区域没有外键引用。

这对我来说似乎是一个非常笨拙的解决方案。有更好的方法吗？

我可以对表进行更改并且数据显示是必要的。

----------------------------------- edit ----------- ------------------------

我让尼克巴恩斯的回答对我来说是这样的：

SELECT price_est.sau_price_avg
FROM price_est
WHERE
    (price_est.county_id = _county_id OR price_est.county_id IS NULL) AND
    (price_est.municipality_id = _municipality_id OR price_est.municipality_id IS NULL) AND
    (price_est.district_id = _district_id OR price_est.district_id IS NULL) AND
    (price_est.neighbourhood_id = _neighbourhood_id OR price_est.neighbourhood_id IS NULL)
ORDER BY price_est.neighbourhood_id NULLS LAST,
         price_est.district_id NULLS LAST,
         price_est.municipality_id NULLS LAST,
         price_est.county_id NULLS LAST
LIMIT 1;

Answer 1

您可以同时选择它们，并使用ORDER BY / LIMIT按照准确性排列优先顺序：

SELECT price_est.sau_price_avg
INTO _est_price
FROM price_est
WHERE
  (price_est.neighbourhood_id = _neighbourhood_id OR price_est.neighbourhood_id IS NULL) AND
  price_est.district_id = _district_id AND
  price_est.municipality_id = _municipality_id AND
  price_est.county_id = _county_id
ORDER BY price_est.neighbourhood_id NULLS LAST
LIMIT 1;

请注意，NULLS LAST是默认排序，因此并非绝对必要，但在这种情况下明确表达您的意图是件好事。

选择postgreSQL中可用的最准确数据？

1 个答案: