Merge pull request #198 from DataObjects-NET/7.0-mssql-datediffbig

Change DATEDIFF to DATEDIFF_BIG for Sql Server v13+

Author: alex-kulakov

Orm/Xtensive.Orm.SqlServer/Sql.Drivers.SqlServer/v13/Compiler.cs

@@ -1,13 +1,48 @@
-// Copyright (C) 2018 Xtensive LLC.
-// All rights reserved.
-// For conditions of distribution and use, see license.
+// Copyright (C) 2018-2021 Xtensive LLC.
+// This code is distributed under MIT license terms.
+// See the License.txt file in the project root for more information.
 // Created by: Alexey Kulakov
 // Created:    2018.09.21
 
+using Xtensive.Sql.Dml;
+
 namespace Xtensive.Sql.Drivers.SqlServer.v13
 {
   internal class Compiler : v12.Compiler
   {
+    protected const string DayPart = "DAY";
+    protected const string MillisecondPart = "MS";
+    protected const string NanosecondPart = "NS";
+    protected const string ZeroTime = "'00:00:00.0000000'";
+
+    /// <inheritdoc/>
+    public override void Visit(SqlFunctionCall node)
+    {
+      if (node.FunctionType == SqlFunctionType.DateTimeOffsetTimeOfDay) {
+        DateTimeOffsetTimeOfDay(node.Arguments[0]).AcceptVisitor(this);
+      }
+      else {
+        base.Visit(node);
+      }
+    }
+
+    protected override SqlExpression DateTimeSubtractDateTime(SqlExpression date1, SqlExpression date2)
+    {
+      return DateDiffBigNanosecond(date2, date1);
+    }
+
+    #region Static Helpers
+
+    protected static SqlUserFunctionCall DateDiffBigNanosecond(SqlExpression date1, SqlExpression date2) =>
+      SqlDml.FunctionCall("DATEDIFF_BIG", SqlDml.Native(NanosecondPart), date1, date2);
+
+    private static SqlExpression DateTimeOffsetTimeOfDay(SqlExpression dateTimeOffset) =>
+      DateDiffBigNanosecond(
+        SqlDml.Native(ZeroTime),
+        SqlDml.Cast(dateTimeOffset, new SqlValueType("time")));
+
+    #endregion
+
     public Compiler(SqlDriver driver)
       : base(driver)
     {