diff --git a/src/lib/ProjectM36/DataTypes/SQL/Null.hs b/src/lib/ProjectM36/DataTypes/SQL/Null.hs
index fb09b8f7..d1014675 100644
--- a/src/lib/ProjectM36/DataTypes/SQL/Null.hs
+++ b/src/lib/ProjectM36/DataTypes/SQL/Null.hs
@@ -205,7 +205,10 @@ sqlMax [RelationAtom relIn] =
   case oneTuple relIn of
     Nothing -> pure $ nullAtom IntegerAtomType Nothing -- SQL max of empty table is NULL
     Just oneTup ->
-      pure $ relFold (\tupIn acc -> nullMax acc (newVal tupIn)) (newVal oneTup) relIn
+      if atomTypeForAtom (newVal oneTup) /= IntegerAtomType then
+        Left AtomFunctionTypeMismatchError
+        else
+        pure $ relFold (\tupIn acc -> nullMax acc (newVal tupIn)) (newVal oneTup) relIn
  where
    newVal tupIn = tupleAtoms tupIn V.! 0
    nullMax acc nextVal =
diff --git a/src/lib/ProjectM36/RelationalExpression.hs b/src/lib/ProjectM36/RelationalExpression.hs
index 38a03139..fba9858f 100644
--- a/src/lib/ProjectM36/RelationalExpression.hs
+++ b/src/lib/ProjectM36/RelationalExpression.hs
@@ -880,7 +880,7 @@ evalGraphRefAtomExpr tupIn (FunctionAtomExpr funcName' arguments tid) = do
                 lift $ except (atomTypeVerify expType actType)) zippedArgs
       evaldArgs <- mapM (evalGraphRefAtomExpr tupIn) arguments
       case evalAtomFunction func evaldArgs of
-        Left err -> traceShow ("evalGraphrefAtomExpr"::String, funcName', arguments) $ throwError (AtomFunctionUserError err)
+        Left err -> throwError (AtomFunctionUserError err)
         Right result -> do
           --validate that the result matches the expected type
           _ <- lift $ except (atomTypeVerify (last (funcType func)) (atomTypeForAtom result))
diff --git a/src/lib/ProjectM36/SQL/Convert.hs b/src/lib/ProjectM36/SQL/Convert.hs
index 4f769b19..b34c9d10 100644
--- a/src/lib/ProjectM36/SQL/Convert.hs
+++ b/src/lib/ProjectM36/SQL/Convert.hs
@@ -687,7 +687,10 @@ convertProjection typeF selItems groupBys havingExpr = do
     task <- foldM (convertSelectItem typeF) emptyTask (zip [1::Int ..] selItems)
 --    traceShowM ("convertProjection task"::String, task)
     -- SQL supports only one grouping at a time, but multiple aggregations, so we create the group as attribute "_sql_aggregate" and the aggregations as fold projections on it
-    fGroup <- if not (null (nonAggregates groupInfo)) then
+    fGroup <- if not (null (nonAggregates groupInfo)) ||
+                 (null (nonAggregates groupInfo) && not (null (aggregates groupInfo)))
+                 -- special case: SELECT max(status) FROM city- handle aggregations without GROUP BY                 
+              then
                 pure $ Group (InvertedAttributeNames
                               (S.fromList (map fst (nonAggregates groupInfo)))) "_sql_aggregate"
               else
@@ -1384,7 +1387,7 @@ data GroupByItem = AggGroupByItem ProjectionScalarExpr GroupByExpr |
 data GroupByInfo =
   GroupByInfo { aggregates :: [ProjectionScalarExpr], -- ^ mentioned in group by clause and uses aggregation
                 nonAggregates :: [(AttributeName, GroupByExpr)], -- ^ mentioned in group by clause by not aggregations
-                havingRestriction :: Maybe ProjectionScalarExpr
+                havingRestriction :: Maybe ProjectionScalarExpr                
               }
   deriving (Show, Eq)
 
diff --git a/test/SQL/InterpreterTest.hs b/test/SQL/InterpreterTest.hs
index 916f21b0..ceb2aae0 100644
--- a/test/SQL/InterpreterTest.hs
+++ b/test/SQL/InterpreterTest.hs
@@ -162,8 +162,8 @@ testSelect = TestCase $ do
          "(relation{city Text, status SQLNullable Integer}{tuple{city \"London\", status SQLJust 20}, tuple{city \"Paris\", status SQLJust 30}, tuple{city \"Athens\", status SQLJust 30}})"),
         -- aggregate without grouping
         ("SELECT max(status) as status FROM s",
-         "(((true:{status:=s{status}}):{max:=max(@status)}){max})",
-         "(relation{status SQLNullable Integer}{tuple{status SQLJust 30}})")
+         "(((s group ({all but } as `_sql_aggregate`)):{status:=sql_max( (@`_sql_aggregate`){ status } )}){ status })",
+         "(relation{status SQLNullable Integer}{tuple{status SQLJust 30}})"),
         -- group by having
         -- limit
         -- case when