diff --git a/dbms/src/Functions/DateTimeTransforms.h b/dbms/src/Functions/DateTimeTransforms.h
index f05ab048fcb..1ee552fa630 100644
--- a/dbms/src/Functions/DateTimeTransforms.h
+++ b/dbms/src/Functions/DateTimeTransforms.h
@@ -47,11 +47,12 @@ struct ToDateImpl
 {
     static constexpr auto name = "toDate";
 
-    static inline UInt16 execute(DateTime64::NativeType t, const DateLUTImpl & time_zone)
-    {
-        std::cout << "converting DateTime64 t=" << t << " " << name << std::endl;
-        return UInt16(time_zone.toDayNum(decimalWholePart(DateTime64(t), 9)));
-    }
+//    static inline UInt16 execute(DateTime64::NativeType t, const DateLUTImpl & time_zone)
+//    {
+//        std::cout << "converting DateTime64 t=" << t << " " << name << std::endl;
+//        throw Exception("!!!! INVALID TO DATE FROM DATETIME64 implementation", ErrorCodes::NOT_IMPLEMENTED);
+//        return UInt16(time_zone.toDayNum(decimalWholePart(DateTime64(t), 9)));
+//    }
 
     static inline UInt16 execute(UInt32 t, const DateLUTImpl & time_zone)
     {
diff --git a/dbms/src/Functions/FunctionsConversion.h b/dbms/src/Functions/FunctionsConversion.h
index e7f317adb96..ca83bde2997 100644
--- a/dbms/src/Functions/FunctionsConversion.h
+++ b/dbms/src/Functions/FunctionsConversion.h
@@ -159,15 +159,11 @@ struct ConvertImpl
     }
 };
 
-
 /** Conversion of DateTime to Date: throw off time component.
   */
 template <typename Name> struct ConvertImpl<DataTypeDateTime, DataTypeDate, Name>
     : DateTimeTransformImpl<DataTypeDateTime, DataTypeDate, ToDateImpl> {};
 
-template <typename Name> struct ConvertImpl<DataTypeDateTime64, DataTypeDate, Name>
-    : DateTimeTransformImpl<DataTypeDateTime64, DataTypeDate, ToDateImpl> {};
-
 
 /** Conversion of Date to DateTime: adding 00:00:00 time component.
   */
@@ -180,18 +176,16 @@ struct ToDateTimeImpl
         return time_zone.fromDayNum(DayNum(d));
     }
 
-    static inline UInt32 execute(DateTime64::NativeType d, const DateLUTImpl & time_zone)
+    // no-op conversion from DateTime to DateTime, used in DateTime64 to DateTime conversion.
+    static inline UInt32 execute(UInt32 d, const DateLUTImpl & /*time_zone*/)
     {
-        return time_zone.fromDayNum(DayNum(d));
+        return d;
     }
 };
 
 template <typename Name> struct ConvertImpl<DataTypeDate, DataTypeDateTime, Name>
     : DateTimeTransformImpl<DataTypeDate, DataTypeDateTime, ToDateTimeImpl> {};
 
-template <typename Name> struct ConvertImpl<DataTypeDateTime64, DataTypeDateTime, Name>
-    : DateTimeTransformImpl<DataTypeDateTime64, DataTypeDateTime, ToDateTimeImpl> {};
-
 /// Implementation of toDate function.
 
 template <typename FromType, typename ToType>
@@ -252,10 +246,34 @@ struct ToDateTime64Transform
 
 template <typename Name> struct ConvertImpl<DataTypeDate, DataTypeDateTime64, Name>
     : DateTimeTransformImpl<DataTypeDate, DataTypeDateTime64, ToDateTime64Transform> {};
-
 template <typename Name> struct ConvertImpl<DataTypeDateTime, DataTypeDateTime64, Name>
     : DateTimeTransformImpl<DataTypeDateTime, DataTypeDateTime64, ToDateTime64Transform> {};
 
+/** Conversion of DateTime64 to Date or DateTime: discards fractional part.
+ */
+template <typename Transform>
+struct FromDateTime64Transform
+{
+    static constexpr auto name = "toDateTime64";
+
+    const DateTime64::NativeType scale_multiplier = 1;
+
+    FromDateTime64Transform(UInt32 scale)
+        : scale_multiplier(decimalScaleMultiplier<DateTime64::NativeType>(scale))
+    {}
+
+    inline auto execute(DateTime64::NativeType dt, const DateLUTImpl & time_zone) const
+    {
+        const auto c = decimalSplitWithScaleMultiplier(DateTime64(dt), scale_multiplier);
+        return Transform::execute(static_cast<UInt32>(c.whole), time_zone);
+    }
+};
+
+template <typename Name> struct ConvertImpl<DataTypeDateTime64, DataTypeDate, Name>
+    : DateTimeTransformImpl<DataTypeDateTime64, DataTypeDate, FromDateTime64Transform<ToDateImpl>> {};
+template <typename Name> struct ConvertImpl<DataTypeDateTime64, DataTypeDateTime, Name>
+    : DateTimeTransformImpl<DataTypeDateTime64, DataTypeDateTime, FromDateTime64Transform<ToDateTimeImpl>> {};
+
 
 /** Transformation of numbers, dates, datetimes to strings: through formatting.
   */
@@ -1013,6 +1031,11 @@ private:
 
                 ConvertImpl<LeftDataType, RightDataType, Name>::execute(block, arguments, result, input_rows_count, scale);
             }
+            else if constexpr (IsDataTypeDateOrDateTime<RightDataType> && std::is_same_v<LeftDataType, DataTypeDateTime64>)
+            {
+                const auto * dt64 = assert_cast<const DataTypeDateTime64 *>(block.getByPosition(arguments[0]).type.get());
+                ConvertImpl<LeftDataType, RightDataType, Name>::execute(block, arguments, result, input_rows_count, dt64->getScale());
+            }
             else
                 ConvertImpl<LeftDataType, RightDataType, Name>::execute(block, arguments, result, input_rows_count);