C#

strSQL = "UPDATE users SET access=" + aTextString;

MySqlCommand cmd = new MySqlCommand("UPDATE users SET access=@Access, date=@Date");
cmd.AddWithValue("@Access", aTextString);
cmd.AddWithValue("@Date", DateTime.Now);

Error 1 A local variable named 'mysqlCon' can not be declared in this area because it would give a different meaning to 'mysqlCon', which is already used in a field 'parent or current' to identify something else ...<br />

try
{
    MySqlConnection mysqlCon = new MySqlConnection(strProvider);
    mysqlCon.Open();

MySqlCommand mysqlCon = new MySqlCommand(strSQL); 
mysqlCon.ExecuteNonQuery();

MySqlConnection mysqlCon2 = new MySqlConnection(strProvider);
mysqlCon2.Open();
MySqlCommand mysqlCon2 = new MySqlCommand(strSQL); 
mysqlCon2.ExecuteNonQuery(); 

<br />
Error 1 A local variable named 'mysqlCon2' is already defined in this area...<br />

MySqlCommand mysqlCmd2 = new MySqlCommand(strSQL, mysqlCon);
MySqlDataReader mysqlReader2 = mysqlCmd.ExecuteReader();

Guizzardi wrote:

Now I change the code like this:

MySqlConnection mysqlCon2 = new MySqlConnection(strProvider);
mysqlCon2.Open();
MySqlCommand mysqlCon2 = new MySqlCommand(strSQL);
mysqlCon2.ExecuteNonQuery();

Adding "2" to "mysqlCon" but now the error message is:

Error 1 A local variable named 'mysqlCon2' is already defined in this area...

referring to the third line...

MySqlCommand cmd = new MySqlCommand("DELETE FROM admin" +
                                    " WHERE IndexCollation=@IC");
cmd.Parameters.AddWithValue("@IC", strIndex);
Utilities.DoSQLNonQuery(cmd);
cmd = new MySqlCommand("INSERT INTO admin" +
                       " (IndexCollation, IndexManagement) " +
                       " VALUES (@IC, AES_ENCRYPT(@IN, @PW))");
cmd.Parameters.AddWithValue("@IC", strIndex);
cmd.Parameters.AddWithValue("@IN", username + "|" + password);
cmd.Parameters.AddWithValue("@PW", Credentials);
Utilities.DoSQLNonQuery(cmd);

/// <summary>
/// Execute a non-query on the database
/// </summary>
/// <remarks>A non-query is an INSERT, UPDATE, or similar instruction that does not require a reader.</remarks>
/// <param name="sqlCmd">Command to execute</param>
/// <returns>True if executed ok.</returns>
public static bool DoSQLNonQuery(MySqlCommand cmd)
    {
    string strConnect;
    bool bResult = false;
    try
        {
        strConnect = ConfigurationManager.ConnectionStrings["LoginDatabase"].ConnectionString;
        cmd.Connection = new MySqlConnection(strConnect);
        cmd.Connection.Open();
        cmd.ExecuteNonQuery();
        bResult = true;
        }
    catch (Exception ex)
        {
        StringBuilder body = new StringBuilder("DoSQLNonQuery: " + cmd.CommandText + "\n");
        foreach (MySqlParameter par in cmd.Parameters)
            {
            body.Append(par.ParameterName + "=" + par.Value + "\n");
            }
        Log(body.ToString() + ex.ToString());
        }
    finally
        {
        if (cmd.Connection != null)
            {
            cmd.Connection.Close();
            }
        }
    return bResult;
    }

MySqlConnection mysqlCon2 = new MySqlConnection(strProvider);
mysqlCon2.Open();
strSQL = "UPDATE utenti SET accesso='test' WHERE username='Administrator'";
MySqlCommand mysqlCmd2 = new MySqlCommand(strSQL, mysqlCon2);
MySqlDataReader mysqlReader2 = mysqlCmd2.ExecuteReader();
mysqlCon2.Close();