How to pass datetime from c# to sql correctly?

Question

I have a table and the date-times in it are in the format:

2011-07-01 15:17:33.357

I am taking a c# DateTime when I do a .ToString() on the object I am getting a DateTime in the format:

04/07/2011 06:06:17

I'm wondering how I correctly pass the correct DateTime through because when I run the SQL that is in our code it doesn't work (i.e. select the correct DateTime). I can't use SQL profiler.

This is the code:

//looks to if a user has had any activity in within the last time specified
        public bool IsUserActivitySinceSuppliedTime(int userId, DateTime since)
        {
            //get everything since the datetime specified [usually 5 hours as this is 
            //how long the session lasts for
            string sql = "SELECT * FROM tbl_webLogging WHERE userid = @userid AND DateAdded > @sinceDateTime";

            SqlParameter sinceDateTimeParam = new SqlParameter("@sinceDateTime", SqlDbType.DateTime);
            sinceDateTimeParam.Value = since;

            SqlCommand command = new SqlCommand(sql);
            command.Parameters.AddWithValue("@userid", userId);
            command.Parameters.Add(sinceDateTimeParam);


            using (SqlDataReader DataReader = GetDataReader(command))
            {
                if (DataReader.HasRows)
                {
                    return true;
                }
                else
                {
                    return false;
                }
            }


        }

UPDATE*******************

I have run the following on the data:

SELECT * FROM tbl_webLogging 
WHERE userid = 1 
AND DateAdded > '2011-07-01 07:19:58.000'

And

SELECT * FROM tbl_webLogging 
WHERE userid = 1 
AND DateAdded > '04/07/2011 07:19:58'

One returns 53 records the other returns 69 records. How can this be? And when I pass the DateTime (04/07/2011 07:19:58) from c# to SQL no records show up at all!

How to pass datetime from c# to sql correctly?

2 Answers