CODEWITHSUNDEEP
c#command
Cajux94
Cajux94

Reputation: 127

Having troubles with a command's execution

So, basically what I'm doing is, after adding a diagnosis on the TextBox I'm checking if there is a Diagnosis with the same name already. The connection works fine, however, I'm having difficulties with executing the command in this line here:

 var count = (int)cmd.ExecuteNonQuery();

Here's the full method

 protected void MesmoDiagnostico_ServerValidate(object source, ServerValidateEventArgs args)
    {
        string connectionString = ConfigurationManager.ConnectionStrings["BDClinica"].ConnectionString;
        SqlConnection connection = new SqlConnection(connectionString);
        SqlCommand cmd = new SqlCommand("Select COUNT(*) from Diagnosticos Where Diagnostico_Nome=@Diagnostico_Nome", connection);
        connection.Open();
        cmd.Parameters.AddWithValue("@Diagnostico_Nome", source);
        var count = (int)cmd.ExecuteNonQuery();

        if (count > 0)
        {
            args.IsValid = false;
        }
        else
        {
            args.IsValid = true;
        }

        connection.Close();
    }

Am I missing something? Thanks!

Upvotes: 0

Views: 22

Answers (2)

Philip Stuyck
Philip Stuyck

Reputation: 7467

This is almost the exact code that you need :

SqlConnection con = new SqlConnection(Settings.Default.FrakoConnectionString);
SqlCommand maxcommand = new SqlCommand("SELECT MAX(Counter) AS max FROM ppartikulieren", con);
try
{
    con.Open();
    max = (int)maxcommand.ExecuteScalar() + 1;
}
catch (Exception ex)
{
    MessageBox.Show("Fout bij het plakken:\n" + ex.Message, "Frako planner", MessageBoxButtons.OK, MessageBoxIcon.Error);
    return;
}
finally
{
    con.Close();
}

you can also use a using statement of course. But the point is that you really need to cast the output of ExecuteScalar.

Upvotes: 0

David
David

Reputation: 10708

According to MSDN, ExecuteNonQuery is for executing catalog or UPDATE/INSERT/DELETE operations and returns the number of rows affected. By using a COUNT, you're still looking for "number of rows" but it's being executed as query, not an update.

Since you only want one piece of data, technically the first column of the first row, you can use ExecutScalar instead.

Upvotes: 1

Related Questions