The SQL Anywhere Optimizer has a very extensive set of semantic transformations which are applied in a preoptimization phase, before the join enumeration process starts. The normal views and derived tables are treated exactly in the same way, hence a query using the normal views and a query using derived tables containing the definitions of the views are equivalent and will be optimized in the same way. An example of how extensive the semantic transformations are is given below - the SQL Anywhere Optimizer applied 7 semantic transformations for this query, some of them patented in 2008.

Original query:

SELECT [Project9].[ContactID] AS [ContactID],[Project9].[C1] AS [C1],[Project9].[C2] AS [C2],[Project9].[ContactID1] AS [ContactID1],[Project9].[SalesOrderID] AS [SalesOrderID], [Project9].[TotalDue] AS [TotalDue] FROM ( SELECT         [Distinct1].[ContactID] AS [ContactID],        1 AS [C1],        [Project8].[ContactID] AS [ContactID1],        [Project8].[SalesOrderID] AS [SalesOrderID],         [Project8].[TotalDue] AS [TotalDue],        [Project8].[C1] AS [C2]         FROM   (SELECT DISTINCT   [Extent1].[ContactID] AS [ContactID]                 FROM  [DBA].[Contact] AS [Extent1]                 INNER JOIN [DBA].[SalesOrderHeader] AS [Extent2] ON  EXISTS (SELECT   cast(1 as bit) AS [C1]                         FROM    ( SELECT cast(1 as bit) AS X ) AS [SingleRowTable1]                         LEFT OUTER JOIN  (SELECT [Extent3].[ContactID] AS [ContactID]                                 FROM [DBA].[Contact] AS [Extent3]  WHERE [Extent2].[ContactID] = [Extent3].[ContactID] )AS [Project1] ON cast(1 as bit) = cast(1 as bit)                         LEFT OUTER JOIN  (SELECT  [Extent4].[ContactID] AS [ContactID]                                 FROM [DBA].[Contact] AS [Extent4]  WHERE [Extent2].[ContactID] = [Extent4].[ContactID] ) AS [Project2] ON cast(1 as bit) = cast(1 as bit)                         WHERE ([Extent1].[ContactID] = [Project1].[ContactID]) OR (([Extent1].[ContactID] IS NULL) AND ([Project2].[ContactID] IS NULL))  ) ) AS [Distinct1]   LEFT OUTER JOIN  (SELECT [Extent5].[ContactID] AS [ContactID],  [Extent6].[SalesOrderID] AS [SalesOrderID], [Extent6].[TotalDue] AS [TotalDue],   1 AS [C1]                 FROM  [DBA].[Contact] AS [Extent5]            INNER JOIN [DBA].[SalesOrderHeader] AS [Extent6] ON  EXISTS (SELECT    cast(1 as bit) AS [C1]                         FROM    ( SELECT cast(1 as bit) AS X ) AS [SingleRowTable2]                         LEFT OUTER JOIN  (SELECT [Extent7].[ContactID] AS [ContactID]                                 FROM [DBA].[Contact] AS [Extent7]  WHERE [Extent6].[ContactID] = [Extent7].[ContactID] )AS [Project5] ON cast(1 as bit) = cast(1 as bit)                         LEFT OUTER JOIN  (SELECT  [Extent8].[ContactID] AS [ContactID]                                 FROM [DBA].[Contact] AS [Extent8]  WHERE [Extent6].[ContactID] = [Extent8].[ContactID] )AS [Project6] ON cast(1 as bit) = cast(1 as bit)   WHERE ([Extent5].[ContactID] = [Project5].[ContactID]) OR (([Extent5].[ContactID] IS NULL) AND ([Project6].[ContactID] IS NULL))                 ) ) AS [Project8] ON ([Project8].[ContactID] = [Distinct1].[ContactID]) OR (([Project8].[ContactID] IS NULL) AND ([Distinct1].[ContactID] IS NULL)) )  AS [Project9] ORDER BY [Project9].[ContactID] ASC, [Project9].[C2] ASC

After semantic transformations applied by the SQL Anywhere Optimizer:

select  Distinct1.ContactID as ContactID as ContactID,  1 as C1 as C1,  1 as C1 as C2 as C2, Extent6.ContactID as ContactID as ContactID1 as ContactID1,   Extent6.SalesOrderID as SalesOrderID as SalesOrderID as SalesOrderID, Extent6.TotalDue as TotalDue as TotalDue as TotalDue from(select distinct  Extent2.ContactID as ContactID      from DBA.SalesOrderHeader as Extent2) as Distinct1(ContactID)        left outer join DBA.SalesOrderHeader as Extent6,     on Extent6.ContactID as ContactID = Distinct1.ContactID order by Distinct1.ContactID as ContactID asc