You cannot create Computed Columns (columns whose value depends upon other rows at the time of insert). The way to handle this is to either use a Stored Procedure to do your insert and put the logic for the computed column in there, or to use a CLR Trigger and compute the column value at the time of insert.
VistaDB has no concept for Global Temp tables. Temp tables and table variable parameters live for the lifetime of the current connection or function depending upon how they are allocated. In order to share data across connections globally we would recommend you create a special table in your database for the purpose, or do it in your application code.
Extended properties in SQL Server may be assigned to almost any ObjectID. VistaDB has no similar construct.
Table and Column descriptions are unique to VistaDB and cannot upsize since SQL Server does not have the construct for them. They could however be implemented as extended properties on the table object. We may add this as a way to the upsize and not lose the metadata in the future.
ExecuteResultSet is not a part of the ADO.NET 2 specification. This is an extended method that Microsoft implemented just for SQL CE. Since this is not a part of the SQL Server library, or a part of the specification, VistaDB has no implementation for this method.
VistaDB does not currently support the DataLength command from SQL Server.
Most of the sp_ commands are not supported. The notable exception is sp_Rename since there is no other SQL Server syntax to rename a table or column.
VistaDB does not support a way to turn off constraint checking on a table.
There are no bulk load operators in VistaDB. Each row must be inserted one at a time.
There are a whole host of operations that SQL Server had for performing rollup and cube operations on data. VistaDB do not support these types of operations. In most cases these are for data reporting purposes, and you can usually do the operation in CLR Code.
VistaDB can chain foreign keys to a greater depth that SQL Server which can lead to compatibility issues if sharing a common schema between VistaDB and SQL Server.