Not implemented SubQuery Exists and NotExists?

[fulviocanducci]

Expected Behavior

SELECT * FROM [User] AS u 
       WHERE EXISTS(SELECT * FROM [Phone] AS p WHERE [p].[UserId] = [u].[Id] )

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SELECT * FROM [User] AS u 
       WHERE NOT EXISTS(SELECT * FROM [Phone] AS p WHERE [p].[UserId] = [u].[Id] )

Actual Behavior

Not implemented