Problem with update command in winform with database

Question

1.00/5 (1 vote)

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created insert update delete in winform with database in sql server database
the problem is when i select the my updated data and click on update button it is showing me that invalid column name?
can anyone plz help me in solving this problem

What I have tried:

private void updatebtn_Click(object sender, EventArgs e)
      {
          {
              try
              {
                  if (comboBox1.Text=="")
                  {
                      MessageBox.Show("enter army number to update");
                  }
                  else
                  {
                      SqlCommand cmdupdate = new SqlCommand("Update insupdel SET name='" + textBox1.Text + "',rank='" + comboBox2.SelectedItem + "' ,unit='" + comboBox3.SelectedItem + "', subunit='" + comboBox4.SelectedItem + "', medicalcategory='" + comboBox5.SelectedItem + "', category='" + comboBox6.SelectedItem+ "',datetimepicker1='"+dateTimePicker1.Text+"'  where armynumber=" + comboBox1.SelectedItem + "", con);
                      con.Open();
                      cmdupdate.CommandType = CommandType.Text;
                      cmdupdate.ExecuteNonQuery();
                      MessageBox.Show("Data Updated");
                  }
              }
              catch (Exception ex)
              {
                  MessageBox.Show(ex.Message);
              }
              finally
              {
                  if (con.State == ConnectionState.Open)
                  {
                      con.Close();
                  }
              }
          }
      }

Posted 22-May-18 18:15pm

Member 13796859

Updated 22-May-18 18:27pm

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Comments

Richard Deeming 23-May-18 13:50pm

Everything you wanted to know about SQL injection (but were afraid to ask) | Troy Hunt[^]
How can I explain SQL injection without technical jargon? | Information Security Stack Exchange[^]
Query Parameterization Cheat Sheet | OWASP[^]

2 solutions

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Dave Kreskowiak · Answer 1 · 2018-05-22T18:28:00

Solution 1

Google for "SQL Injection Attack" to find out why what you're doing is so bad.

Then Google for "C# SQL parameterized queries" to find out how to fix that and probably fix your problem at the same time.

Posted 22-May-18 18:28pm

Dave Kreskowiak

OriginalGriff · Answer 2 · 2018-05-22T18:28:00

Not like that! Never concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Use Parametrized queries instead.

When you concatenate strings, you cause problems because SQL receives commands like:

SQL

SELECT * FROM MyTable WHERE StreetAddress = 'Baker's Wood'

The quote the user added terminates the string as far as SQL is concerned and you get problems. But it could be worse. If I come along and type this instead: "x';DROP TABLE MyTable;--" Then SQL receives a very different command:

SQL

SELECT * FROM MyTable WHERE StreetAddress = 'x';DROP TABLE MyTable;--'

Which SQL sees as three separate commands:

SQL

SELECT * FROM MyTable WHERE StreetAddress = 'x';

A perfectly valid SELECT

SQL

DROP TABLE MyTable;

A perfectly valid "delete the table" command

SQL

--'

And everything else is a comment.
So it does: selects any matching rows, deletes the table from the DB, and ignores anything else.

So ALWAYS use parameterized queries! Or be prepared to restore your DB from backup frequently. You do take backups regularly, don't you?

The chances are that when you've fixed that throughout your whole app, the problem will have gone away as well.