請大家幫忙看一下:為什麼出現這種錯誤呢?

Question

在前面加上：
sqlCommand = new SqlCommand();

Answer 1

這是省略的部分:
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;namespace Reponline
{
/// <summary>
/// Summary description for Form1.
/// </summary>
public class frmReponline : System.Windows.Forms.Form
{
private System.Windows.Forms.GroupBox groLogin;
private System.Windows.Forms.TextBox texPassword;
private System.Windows.Forms.Label labPassword;
private System.Windows.Forms.TextBox texNtaccount;
private System.Windows.Forms.Label labNtaccount;
private System.Windows.Forms.Button butOK;
private System.Windows.Forms.Button butExit;
private System.Windows.Forms.PictureBox picLogo;
private System.Data.SqlClient.SqlConnection sqlConnection;
private System.Data.SqlClient.SqlCommand sqlCommand;
private System.Data.SqlClient.SqlDataReader sqlDataReader;
private string strNtaccount;
private string strRight;
private string strOrg;
private string strOwner;
private string strEmpcode;
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.Container components = null; public frmReponline()
{
//
// Required for Windows Form Designer support
//
InitializeComponent(); //
// TODO: Add any constructor code after InitializeComponent call
//
} /// <summary>
/// Clean up any resources being used.
/// </summary>
protected override void Dispose( bool disposing )
{
if( disposing )
{
if (components != null) 
{
components.Dispose();
}
}
base.Dispose( disposing );
} #region Windows Form Designer generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
System.Resources.ResourceManager resources = new System.Resources.ResourceManager(typeof(frmReponline));
this.groLogin = new System.Windows.Forms.GroupBox();
this.picLogo = new System.Windows.Forms.PictureBox();
this.butExit = new System.Windows.Forms.Button();
this.butOK = new System.Windows.Forms.Button();
this.texPassword = new System.Windows.Forms.TextBox();
this.labPassword = new System.Windows.Forms.Label();
this.texNtaccount = new System.Windows.Forms.TextBox();
this.labNtaccount = new System.Windows.Forms.Label();
this.sqlConnection = new System.Data.SqlClient.SqlConnection();
this.sqlCommand = new System.Data.SqlClient.SqlCommand();
this.groLogin.SuspendLayout();
this.SuspendLayout();
// 
// groLogin
// 
this.groLogin.Controls.AddRange(new System.Windows.Forms.Control[] {
   this.picLogo,
   this.butExit,
   this.butOK,
   this.texPassword,
   this.labPassword,
   this.texNtaccount,
   this.labNtaccount});
this.groLogin.Location = new System.Drawing.Point(3, 1);
this.groLogin.Name = "groLogin";
this.groLogin.Size = new System.Drawing.Size(192, 156);
this.groLogin.TabIndex = 4;
this.groLogin.TabStop = false;
// 
// picLogo
// 
this.picLogo.Image = ((System.Drawing.Bitmap)(resources.GetObject("picLogo.Image")));
this.picLogo.Location = new System.Drawing.Point(8, 88);
this.picLogo.Name = "picLogo";
this.picLogo.Size = new System.Drawing.Size(56, 64);
this.picLogo.TabIndex = 10;
this.picLogo.TabStop = false;
// 
// butExit
// 
this.butExit.Location = new System.Drawing.Point(144, 120);
this.butExit.Name = "butExit";
this.butExit.Size = new System.Drawing.Size(40, 24);
this.butExit.TabIndex = 9;
this.butExit.Text = "退出";
this.butExit.Click += new System.EventHandler(this.butExit_Click);
// 
// butOK
// 
this.butOK.Location = new System.Drawing.Point(96, 120);
this.butOK.Name = "butOK";
this.butOK.Size = new System.Drawing.Size(40, 24);
this.butOK.TabIndex = 8;
this.butOK.Text = "確定";
this.butOK.Click += new System.EventHandler(this.butOK_Click);
// 
// texPassword
// 
this.texPassword.Location = new System.Drawing.Point(112, 66);
this.texPassword.Name = "texPassword";
this.texPassword.PasswordChar = '*';
this.texPassword.Size = new System.Drawing.Size(58, 22);
this.texPassword.TabIndex = 7;
this.texPassword.Text = "";
// 
// labPassword
// 
this.labPassword.Location = new System.Drawing.Point(56, 71);
this.labPassword.Name = "labPassword";
this.labPassword.Size = new System.Drawing.Size(51, 16);
this.labPassword.TabIndex = 6;
this.labPassword.Text = "密    碼";
this.labPassword.TextAlign = System.Drawing.ContentAlignment.MiddleCenter;
// 
// texNtaccount
// 
this.texNtaccount.Location = new System.Drawing.Point(83, 23);
this.texNtaccount.Name = "texNtaccount";
this.texNtaccount.Size = new System.Drawing.Size(61, 22);
this.texNtaccount.TabIndex = 5;
this.texNtaccount.Text = "";
// 
// labNtaccount
// 
this.labNtaccount.Location = new System.Drawing.Point(32, 28);
this.labNtaccount.Name = "labNtaccount";
this.labNtaccount.Size = new System.Drawing.Size(45, 16);
this.labNtaccount.TabIndex = 4;
this.labNtaccount.Text = "帳   號";
this.labNtaccount.TextAlign = System.Drawing.ContentAlignment.MiddleCenter;
// 
// sqlConnection
// 
this.sqlConnection.ConnectionString = "data source=WJDBOA02S;initial catalog=WJWWWDB;password=oauser;persist security in" +
"fo=True;user id=oauser";
// 
// frmReponline
// 
this.AutoScaleBaseSize = new System.Drawing.Size(5, 15);
this.BackColor = System.Drawing.SystemColors.ActiveBorder;
this.ClientSize = new System.Drawing.Size(200, 165);
this.Controls.AddRange(new System.Windows.Forms.Control[] {
  this.groLogin});
this.ForeColor = System.Drawing.SystemColors.Desktop;
this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedSingle;
this.Icon = ((System.Drawing.Icon)(resources.GetObject("$this.Icon")));
this.MaximizeBox = false;
this.MinimizeBox = false;
this.Name = "frmReponline";
this.Text = "線上報修管理系統";
this.Load += new System.EventHandler(this.frmReponline_Load);
this.groLogin.ResumeLayout(false);
this.ResumeLayout(false); }
#endregion /// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]

Answer 2

這一句:
this.sqlCommand = new System.Data.SqlClient.SqlCommand();
就是sqlCommand=new sqlCommand()的意思呀

Answer 3

第二次的时候必须保证以下值为空!         
strNtaccount="";
strOrg="";
strEmpcode="";
strOwner= "";
strRight="";