LinqTOEntities difference beteen Exists and contains [closed]

问题

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Closed 6 years ago.

what is the difference between using exists over contains

var s = new int[] { 1, 2, 3, 4, 5 };
dbset.where(x => s.contains(x.id);

or

var s = new int[] { 1, 2, 3, 4, 5 };
dbset.Where(x => s.Exists(y => x.id));

回答1:

1. Exists is a method of List<T>, there is no such method on array or IEnumerable<T> extensions.
2. Correct syntax of usage of this method is x => s.Exists(y => y == x.id) (you should pass predicate, i.e. method which returns boolean)
3. The difference is - Contains supported by Linq to Entities, Exists is not supported.

来源：https://stackoverflow.com/questions/15481272/linqtoentities-difference-beteen-exists-and-contains