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c#asp.net-mvclinq-to-sqlwhere-clause
Darcy
Darcy

Reputation: 5368

if-else equivalent via linq-to-sql query in where clause c#

Basically I wanted to have an if-else statement in my linq to sql statement.

var query = from d in database
            if(x == y) {
                where d.Attr = x
            }
            else {
                 where d.Attr = y
            }
            select d;

Any ideas?

Upvotes: 3

Views: 4549

Answers (6)

naveen
naveen

Reputation: 1

var query = from d in database where (x == y)? d.Attr = x : d.Attr = y select d;

Upvotes: 0

Venemo
Venemo

Reputation: 19067

This is the solution, assuming you meant == and not =:

var query = from d in database
            where (x == y ? d.Attr == x : d.Attr == y)
            select d;

However, this is logically equal to the following:

var query = from d in database
            where d.Attr == y
            select d;

Because, if x == y is true, then d.Attr == x and d.Attr == y will be equal.

Upvotes: 0

tvanfosson
tvanfosson

Reputation: 532465

Isn't that just the same as

var query = from d in database
            where d.Attr == y
            select d;

Your situation (or a similar, more realistic one) can be handled with a simple conditional in the where clause. For more complex queries you can use the extension methods to build up a query implementing conditionals pretty easily or use a PredicateBuilder to create arbitrarily complex conditions.

var query = db.Table;
if (x == y)
{
   query = query.Where( d.Attr == z );
}
else
{
   query = query.Where( d.Attr == t );
}

var predicate = PredicateBuilder.True<Foo>()
                                .And( f => f.Attr == y )
                                .And( f => f.Attr == x )
                                .Or( f => f.Attr == z );
var query = db.Foo.Where( predicate );

Upvotes: 7

Greg Olmstead
Greg Olmstead

Reputation: 1551

wouldnt 

if(x == y) { 
                where d.Attr = x 
            }

be the same as 

if(x == y) { 
                where d.Attr = y 
            }

if x==y?

so couldnt you just use 

where d.Attr = y

Upvotes: 0

Frank Krueger
Frank Krueger

Reputation: 70993

Supposing, you meant == and not =:

from d in database
where (x == y && d.Attr == x) ||
      (x != y && d.Attr == y)
select d;

Upvotes: 8

Daniel Plaisted
Daniel Plaisted

Reputation: 16744

EDIT: I think I may have misunderstood what you wanted to do.

I'm not sure if the ? (ternary) operator will work in Linq to SQL, but try this:

from d in database select (x == y) ? x : y

Upvotes: 0

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