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?
Supposing, you meant == and not =:
from d in database
where (x == y && d.Attr == x) ||
(x != y && d.Attr == y)
select d;
database, it would be better to move the if outside the LINQ queryx==y will have the same truth value for all elements of database, there is no reason to translate both d.Attr == x and d.Attr == y to SQL.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 );
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
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
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.
var query = from d in database where (x == y)? d.Attr = x : d.Attr = y select d;
