From 118054678805f2498b8eac0d4685d6977f4493ae Mon Sep 17 00:00:00 2001
From: Adam Chlipala <adamc@hcoop.net>
Date: Thu, 25 Feb 2010 14:55:35 -0500
Subject: Use COALESCE to hide NULL results of aggregate functions; fix bug
 with improper ordering of query result columns

---
 src/cjr_print.sml |  4 ++--
 src/monoize.sml   | 20 ++++++++++++++++----
 2 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/src/cjr_print.sml b/src/cjr_print.sml
index fae01db1..f0038de6 100644
--- a/src/cjr_print.sml
+++ b/src/cjr_print.sml
@@ -1657,8 +1657,8 @@ fun p_exp' par env (e, loc) =
                                                 map (fn (x', t) => ("__uwf_" ^ ident x ^ ".__uwf_" ^ ident x', t)) xts)
                                             tables
 
-            val outputs = exps @ tables
-            val outputs = ListMergeSort.sort (fn ((s1, _), (s2, _)) => String.compare (s1, s2) = GREATER) outputs
+            val sort = ListMergeSort.sort (fn ((s1, _), (s2, _)) => String.compare (s1, s2) = GREATER)
+            val outputs = sort exps @ sort tables
 
             val wontLeakStrings = notLeaky env true state
             val wontLeakAnything = notLeaky env false state
diff --git a/src/monoize.sml b/src/monoize.sml
index 21624ab6..0e122c29 100644
--- a/src/monoize.sml
+++ b/src/monoize.sml
@@ -2358,7 +2358,7 @@ fun monoExp (env, st, fm) (all as (e, loc)) =
               (L.EFfi ("Basis", "sql_count"), _),
               _), _),
              _), _),
-            _) => ((L'.EPrim (Prim.String "COUNT(*)"), loc),
+            _) => ((L'.EPrim (Prim.String "COALESCE(COUNT(*),0)"), loc),
                    fm)
 
           | L.ECApp (
@@ -2369,17 +2369,29 @@ fun monoExp (env, st, fm) (all as (e, loc)) =
                _), _),
               _), _),
              _), _),
-            _) =>
+            t) =>
             let
+                val default =
+                    case #1 t of
+                        L.CFfi ("Basis", s) =>
+                        (case s of
+                             "int" => "0"
+                           | "float" => "0.0"
+                           | "string" => "''"
+                           | "time" => "0"
+                           | _ => raise Fail "Illegal type of sql_aggregate [1]")
+                      | _ => raise Fail "Illegal type of sql_aggregate [2]"
+
                 val s = (L'.TFfi ("Basis", "string"), loc)
                 fun sc s = (L'.EPrim (Prim.String s), loc)
             in
                 ((L'.EAbs ("c", s, (L'.TFun (s, (L'.TFun (s, s), loc)), loc),
                            (L'.EAbs ("e1", s, (L'.TFun (s, s), loc),
-                                     strcat [(L'.ERel 1, loc),
+                                     strcat [sc "COALESCE(",
+                                             (L'.ERel 1, loc),
                                              sc "(",
                                              (L'.ERel 0, loc),
-                                             sc ")"]), loc)), loc),
+                                             sc (")," ^ default ^ ")")]), loc)), loc),
                  fm)
             end
 
-- 
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