Problem with inserting data into SQL database in ASP

Question

1.00/5 (1 vote)

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The code displays such an error:
System.Data.SqlClient.SqlException: „Incorrect syntax near '-'.”

The purpose of the code is to insert a numerical data entered by the user into the textbox (into column "ilosc") if there is no such column "odmiany" in the database, or to add the numerical value in the textbox to the number already in the database in the "ilosc" column.

my code:

sql = "select count(*) from zapasy_2020-21  where login='" + Context.User.Identity.Name + "' and odmiana='" + odmiany.SelectedValue + "'";
                  SqlCommand cmd = new SqlCommand(sql, con);

                  con.Open();
                  ros = (int)cmd.ExecuteScalar();

                  con.Close();

                  if (ros > 0)
                  {
                      sql = "select ilosc from zapasy_2020-21  where login='" + Context.User.Identity.Name + "' and odmiana='" + odmiany.SelectedValue + "'";
                      SqlCommand cmq = new SqlCommand(sql, con);
                      con.Open();
                      int ilo = (int)cmq.ExecuteScalar();
                      con.Close();

                      sql = "insert into zapasy_2020-21 values (@ilosc) where login='" + Context.User.Identity.Name + "' and odmiana='" + odmiany.SelectedValue + "'";
                      con.Open();
                      SqlCommand cma = new SqlCommand(sql, con);
                      string y = TextBox1.Text;
                      int z;
                      z = int.Parse(y);

                      SqlParameter paramName = new SqlParameter();
                      paramName.ParameterName = "@ilosc";
                      paramName.Value = ilo + z;

                      cma.Parameters.AddWithValue("ilosc", paramName);


                      int i = cma.ExecuteNonQuery();
                      con.Close(); // connection close

                  }
                  else
                  {




                      sql = "insert into zapasy_2020-21 values (@login,@odmiana,@ilosc)";
                      con.Open();
                      SqlCommand cmk = new SqlCommand(sql, con);
                      string y = TextBox1.Text;
                      int z;
                      z = int.Parse(y);
                      cmk.Parameters.AddWithValue("login", Context.User.Identity.Name);
                      cmk.Parameters.AddWithValue("odmiana", odmiany.SelectedValue);
                      cmk.Parameters.AddWithValue("ilosc", z);

                      int i = cmk.ExecuteNonQuery();
                      con.Close(); // connection close


                  }

What I have tried:

i tried to change sql queries, but i don't know which member is invalid

Posted 4-Dec-20 6:41am

Łukasz Szeszycki

Updated 4-Dec-20 10:32am

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CHill60 7-Dec-20 8:37am

Did you get this sorted out?

1 solution

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BabyYoda · Answer 1 · 2020-12-04T07:31:00

Solution 1

You need to switch to parameterized queries for several reasons. Most importantly to avoid sql injection issues. Right now your code could easily be hacked and your database compromised. Secondly, you'll avoid the syntax issues.

Something like:

C#

using (SqlConnection sqlCon = new SqlConnection("connection string"){
  sqlCon.Open();
  String sql = "select count(*) from zapasy_2020-21  where login= @username and odmiana= @odm";
  using (SqlCommand cmd = new SqlCommand(sql, sqlCon){
      cmd.Parameters.AddWithValue("@username", Context.User.Identity.Name);
      cmd.Parameters.AddWithValue("@odm", odmiany.SelectedValue);
      ...
   }
 }

Posted 4-Dec-20 7:31am

BabyYoda

Comments

Łukasz Szeszycki 4-Dec-20 16:10pm

when I use this code, shows me an error "an unassigned variable was used" (cmd)

BabyYoda 4-Dec-20 16:23pm

I'd have to see the rest of your code. But basically, you just need to fix something. What I gave is not complete, you need to make it work in your code.

Łukasz Szeszycki 4-Dec-20 16:29pm

Yes, i know, but when i write SqlCommand with using , visual shows me a problem with cmd that "an unassigned variable was used". I could send you all my code :)

BabyYoda 4-Dec-20 16:46pm

No, just post the relevant part.