LINQ to SQL Select Distinct by Multiple Columns and return entire entity
I am working with a third party database and need to select a distinct set of data for the specific market that I am looking into. The data is the same for each market, so it is redundant to pull it all in,开发者_如何学C and I don't want to hardcode any logic around it as we are working with the vendor to fix the issue, but we need a fix that will work with the vendors fix as well as the way the database is currently as it could be some time before thier fix goes live.
I do not want to group by anything as I want to get the data at the lowest level, but I don't want any redundant data. My current query looks similar to this...
determinantData = (from x in dbContext.Datas
where x.Bar.Name.Equals(barName) &&
x.Something.Name.Equals(someName) &&
FooIds.Contains(x.Foo.Id) &&
x.Date >= startDate &&
x.Date <= endDate
select x).Distinct();
This does not do what I expect. I would like to select the distinct records by three properties, say Foo
, Bar
, and Something
but return the entire object. How can I do this using LINQ?
You could use group by
with the properties that you want to be distinct, then select the first item of each group:
determinantData = (from x in dbContext.Datas
where x.Bar.Name.Equals(barName) &&
x.Something.Name.Equals(someName) &&
FooIds.Contains(x.Foo.Id) &&
x.Date >= startDate &&
x.Date <= endDate
group x by new { x.Foo, x.Bar, x.Something } into market
select market).Select( g=> g.First());
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