add support for full table aliases

Language/SQL/SimpleSQL/Parser.lhs

@@ -507,7 +507,8 @@ attempt to fix the precedence and associativity. Doesn't work
 >                ,return Nothing
 >                ]
 >     alias j = let a1 = optional (try (keyword_ "as")) *> identifierString
->               in option j (JoinAlias j <$> try a1)
+>                   a2 = optionMaybe (try $ parens (commaSep1 identifierString))
+>               in option j (JoinAlias j <$> try a1 <*> try a2)
 
 > optionalScalarExpr :: String -> P (Maybe ScalarExpr)
 > optionalScalarExpr k = optionMaybe (try (keyword_ k) *> scalarExpr)

Language/SQL/SimpleSQL/Pretty.lhs

@@ -157,7 +157,9 @@ back into SQL source text. It attempts to format the output nicely.
 >         ,nest 4 $ commaSep $ map tr ts]
 >   where
 >     tr (SimpleTableRef t) = text t
->     tr (JoinAlias t a) = tr t <+> text "as" <+> text a
+>     tr (JoinAlias t a cs) =
+>         tr t <+> text "as" <+> text a
+>         <+> maybe empty (\cs' -> parens $ commaSep $ map text cs') cs
 >     tr (JoinParens t) = parens $ tr t
 >     tr (JoinQueryExpr q) = parens $ queryExpr q
 >     tr (JoinTableRef jt t0 t1 jc) =

Language/SQL/SimpleSQL/Syntax.lhs

@@ -99,7 +99,7 @@
 > data TableRef = SimpleTableRef String
 >               | JoinTableRef JoinType TableRef TableRef (Maybe JoinCondition)
 >               | JoinParens TableRef
->               | JoinAlias TableRef String
+>               | JoinAlias TableRef String (Maybe [String])
 >               | JoinQueryExpr QueryExpr
 >                 deriving (Eq,Show)