Object reference not set to an instance of an object. asp.net

Question

i am trying to update my data from webservice to my database. But once i click invoke in the web service page , and run to this command:"command1.Connection.Open();" i will receive this error message :Object reference not set to an instance of an object.

this is my code:

  [WebMethod]
        public void UpdateParticulars(string Name, string CLass, string NRIC, float AmountSpent)
        {
            using (SqlConnection conn = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["ncpConnectionString2"].ConnectionString))
            {
                SqlCommand command1 = new SqlCommand("UPDATE Student set Name=@Name, Class=@CLass,StallNo=@StallNo,AmountSpent=@AmountSpent WHERE NRIC = '" + NRIC + "'");

                command1.Parameters.AddWithValue("@Name", Name);
                command1.Parameters.AddWithValue("@Class", CLass);
                command1.Parameters.AddWithValue("@NRIC", NRIC);
                command1.Parameters.AddWithValue("@AmountSpent", AmountSpent);

                command1.Connection.Open();
                command1.ExecuteNonQuery();
            }
        }

having this error : System.Data.SqlClient.SqlException: Must declare the scalar variable "@StallNo". — Por Weiting
– Por Weiting, Commented Jul 26, 2013 at 7:14
you have added that paramater. Add this command1.Parameters.AddWithValue("@StallNo", ""); — Raghubar
– Raghubar, Commented Jul 26, 2013 at 7:24

gzaxx · Accepted Answer · 2013-07-26 07:04:02Z

8

Pass your SqlConnection as argument to SqlCommand constructor.

SqlCommand command1 = new SqlCommand(query, conn);

Also change your query to be fully parametrized (and you are missing @StallNo parameter):

"UPDATE Student set Name=@Name, Class=@CLass,StallNo=@StallNo,AmountSpent=@AmountSpent WHERE NRIC = @NRIC"

command1.Parameters.AddWithValue("@Name", Name);
command1.Parameters.AddWithValue("@Class", CLass);
command1.Parameters.AddWithValue("@NRIC", NRIC);
command1.Parameters.AddWithValue("@AmountSpent", AmountSpent);
command1.Parameters.AddWithValue("@StallNo", ""); //missing parameter

answered Jul 26, 2013 at 7:04

gzaxx

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2 Comments

Por Weiting Over a year ago

i got this errror: System.Data.SqlClient.SqlException: Must declare the scalar variable "@StallNo".

gzaxx Over a year ago

I pointed that out in my answer (and you are missing @StallNo parameter): must add this command1.Parameters.AddWithValue("@StallNo", ""); //missing parameter with proper value.

user2546623 · Accepted Answer · 2013-07-26 07:15:54Z

0

use command1.Connection=conn; conn.Open();

Before executing ExecuteNonQuery()

answered Jul 26, 2013 at 7:15

user2546623

Comments

user1193035 · Accepted Answer · 2013-07-26 07:17:53Z

0

Just add this line

conn.open();

instead of

command1.Connection.Open();

answered Jul 26, 2013 at 7:17

user1193035

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