Add checks for duplicated column names on insert/update.

Author: rspeele

src/Rezoom.SQL.Compiler/Error.fs

@@ -149,6 +149,10 @@ let cannotCollateType typeName =
     sprintf "SQ063: A column of type ``%O`` cannot have a collation applied" typeName
 let cannotAlterPrimaryKeyColumn columnName =
     sprintf "SQ064: Cannot alter the column ``%O`` because it is part of the table's primary key" columnName
+let insertDuplicateColumn columnName =
+    sprintf "SQ065: The column ``%O`` is specified multiple times in the insert statement" columnName
+let updateDuplicateColumn columnName =
+    sprintf "SQ066: The column ``%O`` is specified multiple times in the update statement" columnName
 
 let tableNameNotSuitableForPG =
     "SQ069: Table name is not suitable for PG (maybe you thought you were writing R?)"

src/Rezoom.SQL.Compiler/TypeChecker.fs

@@ -721,12 +721,16 @@ type private TypeChecker(cxt : ITypeInferenceContext, scope : InferredSelectScop
                 failAt insert.Columns.[0].Source (Error.insertMissingColumns missingColumns)
         | _ ->
             failAt insert.InsertInto.Source Error.insertIntoNonTable
-        {   With = withClause
-            Or = insert.Or
-            InsertInto = table
-            Columns = columns // we *must* specify these because our order might not match DB's
-            Data = checker.Select(insert.Data, SelfQueryShape.Known(knownShape))
-        }
+        match columns |> tryFindFirstDuplicateBy (fun c -> c.Value) with
+        | None ->
+            {   With = withClause
+                Or = insert.Or
+                InsertInto = table
+                Columns = columns // we *must* specify these because our order might not match DB's
+                Data = checker.Select(insert.Data, SelfQueryShape.Known(knownShape))
+            }
+        | Some duplicate ->
+            failAt duplicate.Source (Error.insertDuplicateColumn duplicate.Value)
 
     member this.Update(update : UpdateStmt) =
         let checker, withClause =
@@ -750,14 +754,18 @@ type private TypeChecker(cxt : ITypeInferenceContext, scope : InferredSelectScop
                     | _ ->
                         failAt name.Source <| Error.noSuchColumnToSet updateTable name.Value
             |]
-        {   With = withClause
-            UpdateTable = updateTable
-            Or = update.Or
-            Set = setColumns
-            Where = Option.map checker.Expr update.Where
-            OrderBy = Option.map (rmap checker.OrderingTerm) update.OrderBy
-            Limit = Option.map checker.Limit update.Limit
-        }
+        match setColumns |> tryFindFirstDuplicateBy (fun (name, _) -> name.Value) with
+        | None ->
+            {   With = withClause
+                UpdateTable = updateTable
+                Or = update.Or
+                Set = setColumns
+                Where = Option.map checker.Expr update.Where
+                OrderBy = Option.map (rmap checker.OrderingTerm) update.OrderBy
+                Limit = Option.map checker.Limit update.Limit
+            }
+        | Some (name, _) ->
+            failAt name.Source (Error.updateDuplicateColumn name.Value)
 
     member this.Stmt(stmt : Stmt) =
         match stmt with

src/Rezoom.SQL.Compiler/Utilities.fs

@@ -215,4 +215,14 @@ type StatefulBuilder() =
     member inline this.For(xs, body) : State<_, _> = State.forLoop xs body
     member inline this.Using(disposable, body) : State<_, _> = State.using disposable body
 
-let stateful = StatefulBuilder()
+let stateful = StatefulBuilder()
+
+let tryFindFirstDuplicateBy (selector : _ -> _) (xs : _ seq) =
+    let set = HashSet()
+    use enumer = xs.GetEnumerator()
+    let mutable dup = None
+    while enumer.MoveNext() && dup.IsNone do
+        let x = enumer.Current
+        if not (set.Add(selector x)) then
+            dup <- Some x
+    dup

src/Rezoom.SQL.Test/TestTypeErrors.fs

@@ -130,4 +130,19 @@ let ``ambiguous columns`` () =
             from users u
             join usergroupmaps ugm on ugm.userid = u.id
             join groups g on g.id = ugm.groupid
+        """
+
+[<Test>]
+let ``duplicate column insert`` () =
+    expectError (Error.insertDuplicateColumn "Email")
+        """
+            insert into Users(Name, Email, Email) values ('', '', '');
+        """
+
+[<Test>]
+let ``duplicate column update`` () =
+    expectError (Error.updateDuplicateColumn "Name")
+        """
+            update Users set Name = 'foo', Email = 'bar', Name = 'car'
+            where Id = 1
         """