
select toDateTime64(-86400 ,9,'UTC') ==  1969-12-31 00:00:00.000000000

select toDateTime64(-86400.00 ,9,'UTC') ==  1970-01-01 00:00:00.000000000 


However, I expect both outputs to be same. 

Version affected : 22.8
result_column = ConvertImpl<LeftDataType, RightDataType, Name, SpecialTag>::execute(arguments, result_type, input_rows_count);
            }
            return true;
        };
        if (isDateTime64<Name, ToDataType>(arguments))
        {
            
            const ColumnWithTypeAndName & scale_column = arguments[1];
            UInt32 scale = extractToDecimalScale(scale_column);
            if (to_datetime64 || scale != 0) 
            {
                if (!callOnIndexAndDataType<DataTypeDateTime64>(from_type->getTypeId(), call, ConvertDefaultBehaviorTag{}))
                    throw Exception("Illegal type " + arguments[0].type->getName() + " of argument of function " + getName(),
                                    ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
                return result_column;
            }
        }
        if constexpr (std::is_same_v<ToDataType, DataTypeString>)
        {
            if (from_type->getCustomSerialization())
                return ConvertImplGenericToString<ColumnString>::execute(arguments, result_type, input_rows_count);
        }
        bool done;
        if constexpr (to_string_or_fixed_string)
        {
            done = callOnIndexAndDataType<ToDataType>(from_type->getTypeId(), call, ConvertDefaultBehaviorTag{});
        }
        else
        {