"Or" equivalent in Linq Where() lambda expression

Question

Is there a method in Linq where you can use to build SQL strings like "...where (a=1) OR (a=2)"?

Solution 1

You can certainly do it within a Where clause (extension method). If you need to build a complex query dynamically, though, you can use a PredicateBuilder.

 var query = collection.Where( c => c.A == 1 || c.B == 2 );

Or using a PredicateBuilder

 var predicate = PredicateBuilder.False<Foo>();
 predicate = predicate.Or( f => f.A == 1 );
 if (allowB)
 {
    predicate = predicate.Or( f => f.B == 1 );
 }

 var query = collection.Where( predicate );

Solution 2

You can use the standard .NET boolean operators in your single where clause:

MyDataSource.Where(data => data.a == 'a' || data.a == 'b')

Solution 3

You use the all the same operators as in normal C# ===> || for "or" && for "and" etc.

var something = from s in mycollection
                where s.something == 32 || 
                      s.somethingelse == 45 
                select s

Solution 4

in your .Where() call use the standard Boolean 'Or' operator, ||.

var query = items.Where(item => (item == 1 || item == 2));

All the Where call does is a Boolean comparison on anything you want, so you can fill it with as much conditional logic as you wish.

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