MySql provider: DateTime related improvements

- extraction of DateTime type
- v5.6+ uses datetime(6) everywhere, not only in parameters;
  this will fix certain comparisons because before that parameters
  where of datetime(6) type but values were cast to datetime (no ms part)

Author: alex-kulakov

Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_0/Extractor.cs

@@ -1,4 +1,4 @@
-// Copyright (C) 2011-2023 Xtensive LLC.
+// Copyright (C) 2011-2025 Xtensive LLC.
 // This code is distributed under MIT license terms.
 // See the License.txt file in the project root for more information.
 // Created by: Malisa Ncube
@@ -399,6 +399,9 @@ private SqlValueType CreateValueType(IDataRecord row,
         // although they can be read as "scale" and "precision"
         return new SqlValueType(SqlType.Int64);
       }
+      if (typeName.StartsWith("DATETIME", StringComparison.Ordinal)) {
+        return new SqlValueType(SqlType.DateTime);
+      }
 
       if (typeName.StartsWith("TIME")) {
         // "timestamp precision" is saved as "scale", ignoring too

Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_6/ServerInfoProvider.cs

@@ -1,13 +1,32 @@
-// Copyright (C) 2003-2010 Xtensive LLC.
-// All rights reserved.
-// For conditions of distribution and use, see license.
+// Copyright (C) 2013-2025 Xtensive LLC.
+// This code is distributed under MIT license terms.
+// See the License.txt file in the project root for more information.
 // Created by: Alena Mikshina
 // Created:    2013.12.30
 
+using System;
+using Xtensive.Sql.Info;
+
 namespace Xtensive.Sql.Drivers.MySql.v5_6
 {
   internal class ServerInfoProvider : v5_5.ServerInfoProvider
   {
+    /// <inheritdoc/>
+    public override DataTypeCollection GetDataTypesInfo()
+    {
+      var types = base.GetDataTypesInfo();
+
+      var common = DataTypeFeatures.Default | DataTypeFeatures.Nullable | DataTypeFeatures.NonKeyIndexing |
+        DataTypeFeatures.Grouping | DataTypeFeatures.Ordering | DataTypeFeatures.Multiple;
+
+      var index = DataTypeFeatures.Indexing | DataTypeFeatures.KeyConstraint;
+
+      types.DateTime = DataTypeInfo.Range(SqlType.DateTime, common | index,
+         new ValueRange<DateTime>(new DateTime(1000, 1, 1), new DateTime(9999, 12, 31)),
+         "datetime(6)", "datetime", "time(6)", "time");
+      return types;
+    }
+
     // Constructors
 
     public ServerInfoProvider(SqlDriver driver)

Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_6/Translator.cs

@@ -1,6 +1,6 @@
-// Copyright (C) 2003-2010 Xtensive LLC.
-// All rights reserved.
-// For conditions of distribution and use, see license.
+// Copyright (C) 2013-2025 Xtensive LLC.
+// This code is distributed under MIT license terms.
+// See the License.txt file in the project root for more information.
 // Created by: Alena Mikshina
 // Created:    2013.12.30
 
@@ -20,7 +20,7 @@ public override string Translate(SqlCompilerContext context, SqlCast node, NodeS
         case NodeSection.Entry:
           return "CAST(";
         case NodeSection.Exit:
-          return "AS " + Translate(node.Type) + "(6))";
+          return "AS " + Translate(node.Type) + ")";
         default:
           throw new ArgumentOutOfRangeException("section");
         }