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copied!<p>A reader needs an open connection because you retrieve the results one at a time. You'll want to do an <a href="http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlcommand.executenonquery.aspx" rel="noreferrer">ExecuteNonQuery()</a> for inserts, deletes and updates. You also need to close your connection afterwards. The alternative is to wrap your inserts into a loop if you plan to do multiple inserts.</p> <p>There are a couple of ways you can do this. This way is useful if you plan to reuse the same connection object and command object over and over again:</p> <pre><code>public partial class Form1 : Form { SqlConnection _cn; SqlCommand _cmd; const string ConnString = "Enter your connection string here"; readonly string _insertQuery; const string UsernameParm = "@username"; public Form1() { InitializeComponent(); _cn = new SqlConnection(ConnString); _cmd = new SqlCommand(InsertQuery, _cn); _cmd.Parameters.Add(UsernameParm, SqlDbType.VarChar); _insertQuery = String.Format("INSERT INTO checkmultiuser(username) VALUES ({0})", UsernameParm); } private void button1_Click(object sender, EventArgs e) { _cmd.Parameters[UsernameParm].Value = textBox1.Text; try { _cn.Open(); _cmd.ExecuteNonQuery(); } catch (Exception ex) // probably best to catch specific exceptions { // handle it } finally { _cn.Close(); } } } </code></pre> <p><strong>Just be sure to dispose of the connection and command objects (when the form closes or where ever makes the most sense for your application).</strong></p> <p>Using blocks are a safer alternative, but they will dispose of the object each time (although connections use connection pooling by default):</p> <pre><code>public partial class Form1 : Form { const string ConnString = "Enter your connection string here"; readonly string _insertQuery; const string UsernameParm = "@username"; public Form1() { InitializeComponent(); _insertQuery = String.Format("INSERT INTO checkmultiuser(username) VALUES ({0})", UsernameParm); } private void button1_Click(object sender, EventArgs e) { using (var cn = new SqlConnection(ConnString)) { using (var cmd = new SqlCommand(InsertQuery, cn)) { cmd.Parameters.Add(UsernameParm, SqlDbType.VarChar); cmd.Parameters[UsernameParm].Value = textBox1.Text; cn.Open(); cmd.ExecuteNonQuery(); } } } } </code></pre> <p>Any combination will work as well. You could setup the connection once and just wrap the command object in a using block. I know some people are not fans of nested using blocks (since behind the scenes it is try(try finally) finally)).</p>

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