fix of empty projection

LINQ/LINQ/Interpreter/Query/ProjectionExpression.vb

@@ -98,7 +98,13 @@ Namespace Interpreter.Query
                 Next
 
                 If Not skipVal Then
-                    projections.Add(project.Exec(closure))
+                    If project Is Nothing Then
+                        ' 当SELECT投影操作为空的时候，默认不进行投影操作
+                        ' 即返回最原始的变量值
+                        projections.Add(item)
+                    Else
+                        projections.Add(project.Exec(closure))
+                    End If
                 End If
             Next
 

LINQ/test/sqlite.linq

@@ -3,4 +3,4 @@ imports "Sqlite3"
 FROM x as table("GenePathways")
 IN "E:\GCModeller\src\runtime\Darwinism\LINQ\test\xcc.db"
 WHERE x.pid = 11
-ORDER BY x.gid
+ORDER BY gid