使用关联子查询从Select中更新并加入PostgreSQL [英] Update From Select with Correlated Subquery and Join in PostgreSQL
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问题描述
我正在从SQL Server迁移到Postgres,并且在大多数情况下一切正常.问题之一是我无法弄清楚如何使此查询在Postgres中工作:
I am migrating from SQL Server to Postgres and it has gone okay for the most part. One of the issues is that I am unable to figure out how to make this query work in Postgres:
update
"Measure"
set
DefaultStrataId = StrataId
FROM (SELECT "Strata"."MeasureId",
Min("Strata"."index") AS "Index"
FROM "Strata",
"Measure"
WHERE "Strata"."MeasureId" = "Measure"."MeasureId" and "Strata"."StrataId" in (select strataid from point)
GROUP BY "Strata"."MeasureId") a
INNER JOIN strata
ON "Strata"."index" = a."index"
where "Strata"."MeasureId" = "Measure"."MeasureId";
它抱怨:SQL Error [42601]: ERROR: syntax error at or near "FROM"
如何使它工作?
推荐答案
您唯一的目标似乎是从Strata获得最低价值
Your only goal appears to be getting the minimal value from Strata
忽略所有丑陋的引号,并添加一些别名(假设仅存在一个带有最小值的记录):
Omitting all the ugly quotes,and adding some aliasses (assuming that only one record with the minumum value exists) :
UPDATE Measure m
SET DefaultStrataId = s.StrataId
FROM Strata s
WHERE s.MeasureId = m.MeasureId
AND NOT EXISTS (
SELECT * FROM Strata nx
where nx.MeasureId = s.MeasureId
AND nx."index" < s."index"
)
;
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