LINQ , How to get Max ID with "where" condition

I have searched on stack overflow, but find example for max ID only , I want to find Max ID for some particular condition. Something like this 

var nRow = from p in ctx.FormControls
.          where p.FormObjectsId == FormID
.          select Max(p.Id);

How to do it ?

Jon Skeet
people
quotationmark

Well if you really like query expressions, you can express the "filter and projection" and then use the Max extension method:

var query = from p in ctx.FormControls
            where p.FormObjectsId == FormID
            select p.ID;
var maxID = query.Max();

You can do this without the intermediate variable if you want, but I find query expressions get ugly when you need to put them in brackets etc.

I would personally use the overload of Max that allows you to specify the projection inline, however... and at that point, there's no benefit using the query expression form - just use the extension methods and lambda expressions all the way:

var maxID = ctx.FormControls
               .Where(p => p.FormObjectsId == FormID)
               .Max(p => p.ID);

Don't forget that all of this uses deferred execution up until the Max call (which uses immediate execution) - so for example, if this is executing against LINQ to SQL or the Entity Framework, the whole query will be converted to SQL.

people

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