
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
{
        
        if (checkAndGetDataType<DataTypeString>(from_type_untyped.get()))
        {
            return &ConvertImplGenericFromString<ColumnString>::execute;
        }
        else
        {
            if (cast_type == CastType::accurateOrNull)
                return createToNullableColumnWrapper();
            else
                throw Exception{"Conversion from " + from_type_untyped->getName() + " to " + to_type->getName() +
                    " is not supported", ErrorCodes::CANNOT_CONVERT_TYPE};
        }
    }
    WrapperType createArrayWrapper(const DataTypePtr & from_type_untyped, const DataTypeArray & to_type) const