CODEWITHSUNDEEP
c#linq
Vikram Mali
Vikram Mali

Reputation: 125

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 ?

Upvotes: 1

Views: 13498

Answers (5)

Jon Skeet
Jon Skeet

Reputation: 1500215

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.

Upvotes: 2

Royi Namir
Royi Namir

Reputation: 148524

Query syntax : 

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

Upvotes: 0

mituw16
mituw16

Reputation: 5250

Just order by ID Descending, that would by nature get you the max ID. 

var nRow = (from p in ctx.FormControls
           where p.FormObjectsId == FormID
           select p.ID).OrderByDescending(x => x.p.ID);

Upvotes: 0

Habib
Habib

Reputation: 223237

You can do that like:

var max = ctx.FormControls.Where(r => r.FormObjectsID == FormID)
                            .Max(r => r.Id);

With your query expression you can do:

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

Upvotes: 7

Robert P
Robert P

Reputation: 157

something.Where(t => t.something> 0).Max(w => w.other);

or even Max of where

Upvotes: 1

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