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[英]EF Core Linq Query to Select Rows That Match From a List of Possibilities
[英]Perform 'select * from (select * from …)' query in ef core 2.2
我正在嘗試使用實體框架核心2.2在c#中使用與此(SQL)的子查詢執行類似的查詢
select ST_LengthSpheroid(ST_MakeLine(a."Location"),'SPHEROID["WGS 84",6378137,298.257223563]') AS Length
from (select * from "Logs" where "CarId" = 191
order by "Id") as a;
在實體框架> 2.0中,我嘗試執行左聯接,但是使用自定義功能時,遇到了EF核心警告或錯誤。 是否有任何適當的方法來實現該查詢?
這樣的事情行嗎?
select ST_LengthSpheroid(ST_MakeLine(TrackerLogs.Location),'SPHEROID["WGS 84",6378137,298.257223563]') AS Length
from TrackerLogs
where CarId = 191
order by Id
好的,也許有人知道更好的解決方案,但是經過一些研究,我無法使用純 ef內核來實現這一點,因此我使用了FromSql
var queryable = qLogs.FromSql("select * from \"" + tableName + "\" order by \"" + orderField + "\"");
var result = qCars.Select(x => new RouteModel
{
Mileage = Math.Round(
queryable
.Where(y => y.CarId == x.Id)
.Select(y => PostgisExtensions.ST_LengthSpheroid(
PostgisExtensions.ST_MakeLine(
PostgisExtensions.ST_GeomFromText(y.Location.AsText(), PostgisConstants.MetricSrid)
),
PostgisConstants.SpheroidWgs84)
)
.FirstOrDefault() / 1000),
.....
所以,現在我可以orderby
使用子查詢沒有groupby
或distinct on
。 完美運行,沒有任何ef核心警告,並生成預期的查詢:
SELECT ROUND(COALESCE((
SELECT ST_LengthSpheroid(ST_MakeLine(ST_GeomFromText(ST_AsText(x0."Location"), 4326)), 'SPHEROID["WGS 84",6378137,298.257223563]')
FROM (
select * from "Logs" order by "FixedAt"
) AS x0
WHERE (x0."CarId" = x."Id")
LIMIT 1
), 0.0) / 1000.0) AS "Mileage",
.....
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