Must declare scalar variable @subname error

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This is my code. I can't get rid of this error please help.

C#

protected void CheckBoxList1_SelectedIndexChanged(object sender, EventArgs e)
   {
       String strConnString = ConfigurationManager.ConnectionStrings["facultylogConnectionString"].ConnectionString;
       String strQuery = "Insert into selections (subname, selections) VALUES (@subname, @selections) where subname= @subname ";
       SqlConnection con = new SqlConnection(strConnString);
       SqlCommand cmd = new SqlCommand();
       cmd.CommandType = CommandType.Text;
       cmd.CommandText = strQuery;
       cmd.Connection = con;
       cmd.Parameters.AddWithValue("@subname", DropDownList5.SelectedValue);
       string var = string.Empty;
       for (int i = 0; i < CheckBoxList1.Items.Count - 1; i++)
       {
           if (CheckBoxList1.Items[i].Selected)
           {
               var += CheckBoxList1.Items[i].Text.ToString() + ",";

           }
       }
       cmd.Parameters.AddWithValue("@selections", var);
       cmd.Parameters.Clear();
       con.Open();
       cmd.ExecuteNonQuery();
       con.Close();
   }

What I have tried:

I don't know why I keep getting that error above. Even after I remove

where subname= @subname "

Posted 21-Jun-20 1:38am

candijen

Updated 21-Jun-20 2:27am

Patrice T

v3

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Comments

PIEBALDconsult 21-Jun-20 15:40pm

Be sure that the value of the parameter is not null.
And, no, you can't have a WHERE clause on that type of INSERT statement.

2 solutions

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Chris Copeland · Accepted Answer · 2020-06-21T01:49:00

Solution 1

You seem to be clearing the parameters after you've set them with:

cmd.Parameters.Clear();

Posted 21-Jun-20 1:49am

Chris Copeland

Patrice T · Accepted Answer · 2020-06-21T02:03:00

Look ay comments in code.

C#

protected void CheckBoxList1_SelectedIndexChanged(object sender, EventArgs e)
   {
       String strConnString = ConfigurationManager.ConnectionStrings["facultylogConnectionString"].ConnectionString;
       String strQuery = "Insert into selections (subname, selections) VALUES (@subname, @selections) where subname= @subname ";
       SqlConnection con = new SqlConnection(strConnString);
       SqlCommand cmd = new SqlCommand();
       cmd.CommandType = CommandType.Text;
       cmd.CommandText = strQuery;
       cmd.Connection = con;
       cmd.Parameters.AddWithValue("@subname", DropDownList5.SelectedValue); // Here you declare first parameter
       string var = string.Empty;
       for (int i = 0; i < CheckBoxList1.Items.Count - 1; i++)
       {
           if (CheckBoxList1.Items[i].Selected)
           {
               var += CheckBoxList1.Items[i].Text.ToString() + ",";

           }
       }
       cmd.Parameters.AddWithValue("@selections", var); // Here you declare second parameter
       cmd.Parameters.Clear(); // Here you kill parameters 
       con.Open();
       cmd.ExecuteNonQuery(); // and here you execute the query 
       con.Close();
   }