C# combox display items and value

Question

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my combobox..

cbodept and cbocourse

my db tables..

tbldepartment[deptcode,dept_desc]
tblcourse[coursecode,course_desc,deptcode]

What i want:

1. During form load : display all dept_desc in cbodept.

2. cbodept value : i want dept_desc as value to be save to my db.

2. cbodept_SelectedIndexChanged : i want to load all courses in my cbocourse.

3. cbocourse value : i want course_desc as the value to be save in my db.

What I have tried:

private void loadDepartment()
        {
            try
            {
                SqlConnection cnn = new SqlConnection(cs.constring());
                DataSet ds = new DataSet();
                string getEmpSQL = "select deptcode from tbldepartment";
                SqlDataAdapter sda = new SqlDataAdapter(getEmpSQL, cnn);

                sda.Fill(ds);
                cbodept.DataSource = ds.Tables[0];
                cbodept.DisplayMember = ds.Tables[0].Columns[0].ToString();

            }
            catch(Exception ex)
            {
                MessageBox.Show(ex.ToString());
            }
        }

private void loadCourse()
        {
            try
            {
                SqlConnection cnn = new SqlConnection(cs.constring());
                DataSet ds = new DataSet();
                string getEmpSQL = "select coursecode from tblcourse where department= '" + cbodept.Text + "'";
                SqlDataAdapter sda = new SqlDataAdapter(getEmpSQL, cnn);

                sda.Fill(ds);
                cbocourse.DataSource = ds.Tables[0];
                cbocourse.DisplayMember = ds.Tables[0].Columns[0].ToString();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.ToString());
            }
        }

private void cbodept_SelectedIndexChanged(object sender, EventArgs e)
        {
            loadCourse();
        }

Posted 4-May-17 18:19pm

akosisugar

Updated 8-May-17 9:35am

v2

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Comments

Richard Deeming 9-May-17 10:26am

Your code is vulnerable to SQL Injection[^]. NEVER use string concatenation to build a SQL query. ALWAYS use a parameterized query.

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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muhad@ · Answer 1 · 2017-05-04T19:29:00

Solution 3

try
          {
              SqlConnection cnn = new SqlConnection(cs.constring());
              DataSet ds = new DataSet();
              string getEmpSQL = "select deptcode from tbldepartment";
              SqlDataAdapter sda = new SqlDataAdapter(getEmpSQL, cnn);

              sda.Fill(ds);
              cbodept.DataSource = ds.Tables[0].DefaultView;
              cbodept.DisplayMember = ds.Tables[0].Columns["deptcode "].ToString();
              cbodept.ValueMember = ds.Tables[0].Columns["deptcode "].ToString();


          }
          catch (Exception ex)
          {
              MessageBox.Show(ex.ToString());
          }

Posted 4-May-17 19:29pm

muhad@

Comments

muhad@ 5-May-17 2:17am

3. use cbodept_SelectedValueChanged: to load all courses

4. from your code above use: cbocourse.Text to get the selected course_desc

akosisugar 5-May-17 2:55am

try
{
SqlConnection cnn = new SqlConnection(cs.constring());
cnn.Open();
SqlCommand cmd = new SqlCommand("insert into tblenrollment(department)VALUES(@1)", cnn);

cmd.Parameters.AddWithValue("@1",cbodept.ValueMember);

int rows = cmd.ExecuteNonQuery();
MessageBox.Show("Record created!".ToString());
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
}

after saving the .. deptcode is saving no the dept_desc

Eric Mensah · Answer 2 · 2017-05-08T09:35:00

C#

private void LoadDepartment()
{
     var dt = new DataTable();
     var conn = new SqlConnection(connectionString);
     var cmd = new SqlCommand("SELECT deptcode FROM tbldepartment",conn);
     var da = new SqlDataAdapter(cmd);
     dt.Clear();
     da.fill(dt);
     for(DataRow item in dt.Rows)
       {
          cbodept.Items.Add(item[0].ToString());
       }
}

C#

private void LoadCourse()
{
     var dt = new DataTable();
     var conn = new SqlConnection(connectionString);
       var cmd = new SqlCommand("SELECT coursecode FROM tblcourse WHERE    department='"+cbodept.Text+"'",conn);
     var da = new SqlDataAdapter(cmd);
     dt.Clear();
     da.fill(dt);
     for(DataRow item in dt.Rows)
       {
          cbocourse.Items.Add(item[0].ToString());
       }
}
private void cbodept_SelectedIndexChanged(object sender, EventArgs e)
        {
            loadCourse();
        }