与本地字符串值c＃比较后如何在sql server表中存储值

Question

Here is my code...which gives a sorted (descending) list of cosine similarity values of different queries with a document.

   var dd = new List<Tuple<string, double, string>>();

            while ((line = file.ReadLine()) != null)
            {
                dd.Add(Tuple.Create(line, p.calculate_CS(line, document), document));
            }

            var top_value = dd.OrderByDescending(x => x.Item2).FirstOrDefault();

            if (top_value != null)
            { 
                // look up record using top_value.Item3, and then store top_value.Item1
                var abstrct = top_value.Item3.ToString();
                var r_field = top_value.Item1.ToString();

                write_To_Database(abstrct, r_field);
            }

This is the data insertion method......

static void write_To_Database(string document, string research_field)
        {
            try
            {
                SqlConnection con = new SqlConnection("Data Source=KHIZER;Initial Catalog=subset_aminer;Integrated Security=True;");

                con.Open();
                SqlCommand query = con.CreateCommand();
                query.CommandText = "select id from sub_aminer_paper where pid between 1 and 500 and DATALENGTH(p_abstract) != 0 and p_abstract = " + document;

                SqlDataReader reader = query.ExecuteReader();


                reader.Read();
                int id = reader.GetInt32(0);
                //reader.Close();

                query.Parameters.Add("@research_field", SqlDbType.Text);
                query.Parameters.Add("@id", SqlDbType.Int);

                query.CommandText = "insert into sub_aminer_paper (research_area) values(@research_field) where id = @id";
                query.ExecuteNonQuery();


                con.Close();
            }
            catch (Exception e)
            {
                Console.WriteLine("Exception: " + e.Message);
            }
            finally
            {
                Console.WriteLine("Executing finally block.");

            }
        }

I want to store the value of top (highest cosine similarity value) query in database against the string document which is taken from the same table... Table structure is as follows...

--------------------------------------------------------------------------------
id | pid | p_title | p_author | p_year | p_venue | p_abstract | research_area
--------------------------------------------------------------------------------

string document is p_abstract and query is to be saved in the column research_area

Any suggestions will be highly appreciated.

Answer 1

First a bit of code review:

• Don't use underscores in names: write_To_Database , r_field , research_field , top_value , etc.
• Don't abbreviate: r_field , abstrct .
• SqlConnection , SqlCommand , etc. should always be encapsulated in a using so they get properly disposed of.
• Don't do this: p_abstract = " + document; , always work with parameters. Otherwise you risk SQL injection .
• Why do you do a SELECT first and an INSERT after? Why not simply add that WHERE to your INSERT ?
• Why are your names not consistent: research_area vs research_field , document vs abstrct vs p_abstract ?

Now here's your main problem: you do query.Parameters.Add yet nowhere do you add the value. It's as simple as this: cmd.Parameters.Add("@research_field", SqlDbType.Text).Value = research_field; .

However, I'm a bit baffled by the logic of your code: first you go looking for an ID of a record, and then you insert a record with that ID? I find this highly suspect, since I would assume that the ID needs to be unique.