Error Getting Index Number on Database Using C#, Showing -1

Question

i have made a script in C# to get index number on database using someparameter on ComboBox.

private int category(string id) {
        int identity = 0;
        try
        {
            MySqlConnection conn = new MySqlConnection(connection.mysqlconnectionbuilder());
            conn.Open();
            MySqlCommand cmd = conn.CreateCommand();
            cmd.CommandText = "SELECT kategori.no FROM kategori WHERE kategori.kategori = @id";
            cmd.Parameters.AddWithValue("@id", id);
            cmd.CommandType = CommandType.Text;
            identity = cmd.ExecuteNonQuery();
            conn.Close();
        }
        catch (MySqlException msqe)
        {
            Console.Write(msqe.ToString());
        }
        return identity;
    }

I want to get Index number based on name example. "Hollywood Movie" --> ID : 2 (in DB) The result from above script is -1.

How to solve that? thanks in advance.

John Woo · Accepted Answer · 2012-12-31 05:06:08Z

2

use ExecuteScalar() if you want to fetch single value.

identity = Convert.ToInt32(cmd.ExecuteScalar());

ExecuteScalar Method (with example)

answered Dec 31, 2012 at 5:06

John Woo

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1 Comment

randytan Over a year ago

hi @JW thanks for your reply. It's working now. :D cheers and Happy New Year.

Vishal Suthar · Accepted Answer · 2012-12-31 05:19:11Z

0

ExecuteNonQuery will returns the number of rows affected.

It is used for Insert, Update or Delete. It returns an integer specifying the number of rows affected.

So you need to use ExecuteScalar which returns the first column of the first row in the result set returned by the query

"For UPDATE, INSERT, and DELETE statements, the return value is the number of rows affected by the command. For all other types of statements, the return value is -1. If a rollback occurs, the return value is also -1."

identity = Int.Parse(cmd.ExecuteScalar());

edited Dec 31, 2012 at 5:19

answered Dec 31, 2012 at 5:12

Vishal Suthar

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1 Comment

randytan Over a year ago

thanks for your reply @Vishal. Yes, it's using ExecuteScalar and it's working now.

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