LINQ query OrderBy doesn't work

_db.InstellingAdressens
    .Where(l => l.GEMEENTE.Contains(gem_query))
    .OrderBy(q => q.GEMEENTE)
    .Select(q => q.GEMEENTE)
    .Distinct();

this is the query. it returns a List<string> b开发者_如何学Cut the strings are not ordered at all. Why does the OrderBy have no effect? and how to fix it?

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Try putting OrderBy at the end of your call.

_db.InstellingAdressens.
    Where(l => l.GEMEENTE.Contains(gem_query)).
    Select(q=>q.GEMEENTE).Distinct().
    OrderBy(q=>q).ToList();

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Distinct has no knowledge that you have ordered your items before it gets them, so it can't use that knowledge. As such, it has to assume the items are unordered, and will thus just do what it wants with them.

A typical implementation will use a hashtable, which isn't ordered by what you normally want the items to be ordered by, so the result from the distinct operation is an unordered set.

So as others have suggested, change the ordering of your calls to do the ordering last, and you should get what you want.

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Change the order of calls

_db.InstellingAdressens.Where(l => l.GEMEENTE.Contains(gem_query)).Select(q=>q.GEMEENTE).Distinct().OrderBy(q=>q.GEMEENTE).ToList();

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Try this just put orderby last of the query

_db.InstellingAdressens
.Where(l => l.GEMEENTE.Contains(gem_query))
.Select(q=>q.GEMEENTE)
.Distinct()
.OrderBy(q=>q.GEMEENTE).ToList();