add schema support for create index referenced table, and add some tests

Language/SQL/SimpleSQL/Parse.lhs

@@ -1511,7 +1511,7 @@ TODO: change style
 >     <$> ((keyword_ "index" >> pure False) <|>
 >          (keywords_ ["unique", "index"] >> pure True))
 >     <*> names
->     <*> (keyword_ "on" >> name)
+>     <*> (keyword_ "on" >> names)
 >     <*> parens (commaSep1 name)
 
 > columnDef :: Parser ColumnDef

Language/SQL/SimpleSQL/Pretty.lhs

@@ -531,6 +531,15 @@ Try to do this when this code is ported to a modern pretty printing lib.
 > statement _ (DropAssertion nm db) =
 >     text "drop" <+> text "assertion" <+> names nm <+> dropBehav db
 
+> statement _ (CreateIndex un nm tbl cols) =
+>   texts (if un
+>          then ["create","unique","index"]
+>          else  ["create","index"])
+>   <+> names nm
+>   <+> text "on"
+>   <+> names tbl
+>   <+> parens (commaSep $ map name cols)
+
 == dml
 
 > statement d (SelectStatement q) = queryExpr d q

Language/SQL/SimpleSQL/Syntax.lhs

@@ -454,7 +454,7 @@ I'm not sure if this is valid syntax or not.
 >   | CreateTable [Name] [TableElement]
 >   | AlterTable [Name] AlterTableAction
 >   | DropTable [Name] DropBehaviour
->   | CreateIndex Bool [Name] Name [Name]
+>   | CreateIndex Bool [Name] [Name] [Name]
 >   | CreateView Bool [Name] (Maybe [Name])
 >         QueryExpr (Maybe CheckOption)
 >   | DropView [Name]  DropBehaviour