error for sending(saving) data to database

Hi,

I¡¯m using VS2005 and I¡¯m trying to link the C# windows form to MSSQL. I used BindingNavigator Control to read the data. After that I add sqlcommand and sqldataadapter to send the data to the database. My code is this

sqlDataAdapter1.InsertCommand.CommandText =

"INSERT INTO SUDENT (" +

"S_ID, S_NAME, S_ADDRESS, S_PHONE" +

") VALUES ('" +

S_IDComboBox.Text + "', '" +

S_NAMETextBox.Text + "', '" +

S_ADDRESSTextBox.Text + "', '" +

S_PHONETextBox.Text + "')";

sqlDataAdapter1.InsertCommand.ExecuteNonQuery();

It gave me this error

¡°NulleferenceException was Unhandled¡±and ¡° Object refrence not set to an instance of an object¡± so I add this line

sqlCommand1 = ("INSERT INTO STUDENT (S_ID,S_NAME,S_ADDRESS,S_PHONE) VALUES (@S_ID,@S_NAME,@S_ADDRESS,@S_PHONE)" ,sqlConnection1);

Then it gave me some stupid error. By the way it didn¡¯t make a new object of SqlCommand although I tried ¡­.

So can u help me to solve my problem Thank you

Form1.designer.cs

namespace student

partial class Form1

/// <summary>

/// Required designer variable.

/// </summary>

private System.ComponentModel.IContainer components = null;

/// <summary>

/// Clean up any resources being used.

/// </summary>

/// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>

protected override void Dispose(bool disposing)

if (disposing && (components != null))

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()

this.components = new System.ComponentModel.Container();

System.ComponentModel.ComponentResourceManager resources = new System.ComponentModel.ComponentResourceManager(typeof(Form1));

System.Windows.Forms.Label s_IDLabel;

System.Windows.Forms.Label s_NAMELabel;

System.Windows.Forms.Label s_ADDRESSLabel;

System.Windows.Forms.Label s_PHONELabel;

this.studentDataSet = new student.studentDataSet();

this.sTUDENTBindingSource = new System.Windows.Forms.BindingSource(this.components);

this.sTUDENTTableAdapter = new student.studentDataSetTableAdapters.STUDENTTableAdapter();

this.sTUDENTBindingNavigator = new System.Windows.Forms.BindingNavigator(this.components);

this.bindingNavigatorMoveFirstItem = new System.Windows.Forms.ToolStripButton();

this.bindingNavigatorMovePreviousItem = new System.Windows.Forms.ToolStripButton();

this.bindingNavigatorSeparator = new System.Windows.Forms.ToolStripSeparator();

this.bindingNavigatorPositionItem = new System.Windows.Forms.ToolStripTextBox();

this.bindingNavigatorCountItem = new System.Windows.Forms.ToolStripLabel();

this.bindingNavigatorSeparator1 = new System.Windows.Forms.ToolStripSeparator();

this.bindingNavigatorMoveNextItem = new System.Windows.Forms.ToolStripButton();

this.bindingNavigatorMoveLastItem = new System.Windows.Forms.ToolStripButton();

this.bindingNavigatorSeparator2 = new System.Windows.Forms.ToolStripSeparator();

this.bindingNavigatorAddNewItem = new System.Windows.Forms.ToolStripButton();

this.bindingNavigatorDeleteItem = new System.Windows.Forms.ToolStripButton();

this.sTUDENTBindingNavigatorSaveItem = new System.Windows.Forms.ToolStripButton();

this.s_IDTextBox = new System.Windows.Forms.TextBox();

this.s_NAMETextBox = new System.Windows.Forms.TextBox();

this.s_ADDRESSTextBox = new System.Windows.Forms.TextBox();

this.s_PHONETextBox = new System.Windows.Forms.TextBox();

this.sqlConnection1 = new System.Data.SqlClient.SqlConnection();

this.sqlCommand1 = new System.Data.SqlClient.SqlCommand();

this.sqlSelectCommand1 = new System.Data.SqlClient.SqlCommand();

this.sqlInsertCommand1 = new System.Data.SqlClient.SqlCommand();

this.sqlDataAdapter1 = new System.Data.SqlClient.SqlDataAdapter();

s_IDLabel = new System.Windows.Forms.Label();

s_NAMELabel = new System.Windows.Forms.Label();

s_ADDRESSLabel = new System.Windows.Forms.Label();

s_PHONELabel = new System.Windows.Forms.Label();

((System.ComponentModel.ISupportInitialize)(this.studentDataSet)).BeginInit();

((System.ComponentModel.ISupportInitialize)(this.sTUDENTBindingSource)).BeginInit();

((System.ComponentModel.ISupportInitialize)(this.sTUDENTBindingNavigator)).BeginInit();

this.sTUDENTBindingNavigator.SuspendLayout();

this.SuspendLayout();

//

// studentDataSet

//

this.studentDataSet.DataSetName = "studentDataSet";

this.studentDataSet.SchemaSerializationMode = System.Data.SchemaSerializationMode.IncludeSchema;

//

// sTUDENTBindingSource

//

this.sTUDENTBindingSource.DataMember = "STUDENT";

this.sTUDENTBindingSource.DataSource = this.studentDataSet;

//

// sTUDENTTableAdapter

//

this.sTUDENTTableAdapter.ClearBeforeFill = true;

//

// sTUDENTBindingNavigator

//

this.sTUDENTBindingNavigator.AddNewItem = this.bindingNavigatorAddNewItem;

this.sTUDENTBindingNavigator.BindingSource = this.sTUDENTBindingSource;

this.sTUDENTBindingNavigator.CountItem = this.bindingNavigatorCountItem;

this.sTUDENTBindingNavigator.DeleteItem = this.bindingNavigatorDeleteItem;

this.sTUDENTBindingNavigator.Items.AddRange(new System.Windows.Forms.ToolStripItem[] {

this.bindingNavigatorMoveFirstItem,

this.bindingNavigatorMovePreviousItem,

this.bindingNavigatorSeparator,

this.bindingNavigatorPositionItem,

this.bindingNavigatorCountItem,

this.bindingNavigatorSeparator1,

this.bindingNavigatorMoveNextItem,

this.bindingNavigatorMoveLastItem,

this.bindingNavigatorSeparator2,

this.bindingNavigatorAddNewItem,

this.bindingNavigatorDeleteItem,

this.sTUDENTBindingNavigatorSaveItem});

this.sTUDENTBindingNavigator.Location = new System.Drawing.Point(0, 0);

this.sTUDENTBindingNavigator.MoveFirstItem = this.bindingNavigatorMoveFirstItem;

this.sTUDENTBindingNavigator.MoveLastItem = this.bindingNavigatorMoveLastItem;

this.sTUDENTBindingNavigator.MoveNextItem = this.bindingNavigatorMoveNextItem;

this.sTUDENTBindingNavigator.MovePreviousItem = this.bindingNavigatorMovePreviousItem;

this.sTUDENTBindingNavigator.Name = "sTUDENTBindingNavigator";

this.sTUDENTBindingNavigator.PositionItem = this.bindingNavigatorPositionItem;

this.sTUDENTBindingNavigator.Size = new System.Drawing.Size(463, 25);

this.sTUDENTBindingNavigator.TabIndex = 0;

this.sTUDENTBindingNavigator.Text = "bindingNavigator1";

//

// bindingNavigatorMoveFirstItem

//

this.bindingNavigatorMoveFirstItem.DisplayStyle = System.Windows.Forms.ToolStripItemDisplayStyle.Image;

this.bindingNavigatorMoveFirstItem.Image = ((System.Drawing.Image)(resources.GetObject("bindingNavigatorMoveFirstItem.Image")));

this.bindingNavigatorMoveFirstItem.Name = "bindingNavigatorMoveFirstItem";

this.bindingNavigatorMoveFirstItem.RightToLeftAutoMirrorImage = true;

this.bindingNavigatorMoveFirstItem.Size = new System.Drawing.Size(23, 22);

this.bindingNavigatorMoveFirstItem.Text = "Move first";

//

// bindingNavigatorMovePreviousItem

//

this.bindingNavigatorMovePreviousItem.DisplayStyle = System.Windows.Forms.ToolStripItemDisplayStyle.Image;

this.bindingNavigatorMovePreviousItem.Image = ((System.Drawing.Image)(resources.GetObject("bindingNavigatorMovePreviousItem.Image")));

this.bindingNavigatorMovePreviousItem.Name = "bindingNavigatorMovePreviousItem";

this.bindingNavigatorMovePreviousItem.RightToLeftAutoMirrorImage = true;

this.bindingNavigatorMovePreviousItem.Size = new System.Drawing.Size(23, 22);

this.bindingNavigatorMovePreviousItem.Text = "Move previous";

//

// bindingNavigatorSeparator

//

this.bindingNavigatorSeparator.Name = "bindingNavigatorSeparator";

this.bindingNavigatorSeparator.Size = new System.Drawing.Size(6, 25);

//

// bindingNavigatorPositionItem

//

this.bindingNavigatorPositionItem.AccessibleName = "Position";

this.bindingNavigatorPositionItem.AutoSize = false;

this.bindingNavigatorPositionItem.Name = "bindingNavigatorPositionItem";

this.bindingNavigatorPositionItem.Size = new System.Drawing.Size(50, 21);

this.bindingNavigatorPositionItem.Text = "0";

this.bindingNavigatorPositionItem.ToolTipText = "Current position";

//

// bindingNavigatorCountItem

//

this.bindingNavigatorCountItem.Name = "bindingNavigatorCountItem";

this.bindingNavigatorCountItem.Size = new System.Drawing.Size(36, 22);

this.bindingNavigatorCountItem.Text = "of {0}";

this.bindingNavigatorCountItem.ToolTipText = "Total number of items";

//

// bindingNavigatorSeparator1

//

this.bindingNavigatorSeparator1.Name = "bindingNavigatorSeparator";

this.bindingNavigatorSeparator1.Size = new System.Drawing.Size(6, 25);

//

// bindingNavigatorMoveNextItem

//

this.bindingNavigatorMoveNextItem.DisplayStyle = System.Windows.Forms.ToolStripItemDisplayStyle.Image;

this.bindingNavigatorMoveNextItem.Image = ((System.Drawing.Image)(resources.GetObject("bindingNavigatorMoveNextItem.Image")));

this.bindingNavigatorMoveNextItem.Name = "bindingNavigatorMoveNextItem";

this.bindingNavigatorMoveNextItem.RightToLeftAutoMirrorImage = true;

this.bindingNavigatorMoveNextItem.Size = new System.Drawing.Size(23, 22);

this.bindingNavigatorMoveNextItem.Text = "Move next";

//

// bindingNavigatorMoveLastItem

//

this.bindingNavigatorMoveLastItem.DisplayStyle = System.Windows.Forms.ToolStripItemDisplayStyle.Image;

this.bindingNavigatorMoveLastItem.Image = ((System.Drawing.Image)(resources.GetObject("bindingNavigatorMoveLastItem.Image")));

this.bindingNavigatorMoveLastItem.Name = "bindingNavigatorMoveLastItem";

this.bindingNavigatorMoveLastItem.RightToLeftAutoMirrorImage = true;

this.bindingNavigatorMoveLastItem.Size = new System.Drawing.Size(23, 22);

this.bindingNavigatorMoveLastItem.Text = "Move last";

//

// bindingNavigatorSeparator2

//

this.bindingNavigatorSeparator2.Name = "bindingNavigatorSeparator";

this.bindingNavigatorSeparator2.Size = new System.Drawing.Size(6, 25);

//

// bindingNavigatorAddNewItem

//

this.bindingNavigatorAddNewItem.DisplayStyle = System.Windows.Forms.ToolStripItemDisplayStyle.Image;

this.bindingNavigatorAddNewItem.Image = ((System.Drawing.Image)(resources.GetObject("bindingNavigatorAddNewItem.Image")));

this.bindingNavigatorAddNewItem.Name = "bindingNavigatorAddNewItem";

this.bindingNavigatorAddNewItem.RightToLeftAutoMirrorImage = true;

this.bindingNavigatorAddNewItem.Size = new System.Drawing.Size(23, 22);

this.bindingNavigatorAddNewItem.Text = "Add new";

//

// bindingNavigatorDeleteItem

//

this.bindingNavigatorDeleteItem.DisplayStyle = System.Windows.Forms.ToolStripItemDisplayStyle.Image;

this.bindingNavigatorDeleteItem.Image = ((System.Drawing.Image)(resources.GetObject("bindingNavigatorDeleteItem.Image")));

this.bindingNavigatorDeleteItem.Name = "bindingNavigatorDeleteItem";

this.bindingNavigatorDeleteItem.RightToLeftAutoMirrorImage = true;

this.bindingNavigatorDeleteItem.Size = new System.Drawing.Size(23, 22);

this.bindingNavigatorDeleteItem.Text = "Delete";

//

// sTUDENTBindingNavigatorSaveItem

//

this.sTUDENTBindingNavigatorSaveItem.DisplayStyle = System.Windows.Forms.ToolStripItemDisplayStyle.Image;

this.sTUDENTBindingNavigatorSaveItem.Image = ((System.Drawing.Image)(resources.GetObject("sTUDENTBindingNavigatorSaveItem.Image")));

this.sTUDENTBindingNavigatorSaveItem.Name = "sTUDENTBindingNavigatorSaveItem";

this.sTUDENTBindingNavigatorSaveItem.Size = new System.Drawing.Size(23, 22);

this.sTUDENTBindingNavigatorSaveItem.Text = "Save Data";

this.sTUDENTBindingNavigatorSaveItem.Click += new System.EventHandler(this.sTUDENTBindingNavigatorSaveItem_Click);

//

// s_IDLabel

//

s_IDLabel.AutoSize = true;

s_IDLabel.Location = new System.Drawing.Point(44, 52);

s_IDLabel.Name = "s_IDLabel";

s_IDLabel.Size = new System.Drawing.Size(31, 13);

s_IDLabel.Text = "S ID:";

//

// s_IDTextBox

//

this.s_IDTextBox.DataBindings.Add(new System.Windows.Forms.Binding("Text", this.sTUDENTBindingSource, "S_ID", true));

this.s_IDTextBox.Location = new System.Drawing.Point(81, 49);

this.s_IDTextBox.Name = "s_IDTextBox";

this.s_IDTextBox.Size = new System.Drawing.Size(100, 20);

this.s_IDTextBox.TabIndex = 2;

//

// s_NAMELabel

//

s_NAMELabel.AutoSize = true;

s_NAMELabel.Location = new System.Drawing.Point(51, 91);

s_NAMELabel.Name = "s_NAMELabel";

s_NAMELabel.Size = new System.Drawing.Size(51, 13);

s_NAMELabel.Text = "S NAME:";

//

// s_NAMETextBox

//

this.s_NAMETextBox.DataBindings.Add(new System.Windows.Forms.Binding("Text", this.sTUDENTBindingSource, "S_NAME", true));

this.s_NAMETextBox.Location = new System.Drawing.Point(108, 88);

this.s_NAMETextBox.Name = "s_NAMETextBox";

this.s_NAMETextBox.Size = new System.Drawing.Size(100, 20);

this.s_NAMETextBox.TabIndex = 4;

//

// s_ADDRESSLabel

//

s_ADDRESSLabel.AutoSize = true;

s_ADDRESSLabel.Location = new System.Drawing.Point(49, 122);

s_ADDRESSLabel.Name = "s_ADDRESSLabel";

s_ADDRESSLabel.Size = new System.Drawing.Size(72, 13);

s_ADDRESSLabel.Text = "S ADDRESS:";

//

// s_ADDRESSTextBox

//

this.s_ADDRESSTextBox.DataBindings.Add(new System.Windows.Forms.Binding("Text", this.sTUDENTBindingSource, "S_ADDRESS", true));

this.s_ADDRESSTextBox.Location = new System.Drawing.Point(127, 119);

this.s_ADDRESSTextBox.Name = "s_ADDRESSTextBox";

this.s_ADDRESSTextBox.Size = new System.Drawing.Size(100, 20);

this.s_ADDRESSTextBox.TabIndex = 6;

//

// s_PHONELabel

//

s_PHONELabel.AutoSize = true;

s_PHONELabel.Location = new System.Drawing.Point(77, 160);

s_PHONELabel.Name = "s_PHONELabel";

s_PHONELabel.Size = new System.Drawing.Size(58, 13);

s_PHONELabel.Text = "S PHONE:";

//

// s_PHONETextBox

//

this.s_PHONETextBox.DataBindings.Add(new System.Windows.Forms.Binding("Text", this.sTUDENTBindingSource, "S_PHONE", true));

this.s_PHONETextBox.Location = new System.Drawing.Point(141, 157);

this.s_PHONETextBox.Name = "s_PHONETextBox";

this.s_PHONETextBox.Size = new System.Drawing.Size(100, 20);

this.s_PHONETextBox.TabIndex = 8;

//

// sqlConnection1

//

this.sqlConnection1.ConnectionString = "Data Source=.\\SQLEXPRESS;AttachDbFilename=\"C:\\Documents and Settings\\Glad\\Desktop" +

"\\student\\student\\student.mdf\";Integrated Security=True;User Instance=True";

this.sqlConnection1.FireInfoMessageEventOnUserErrors = true;

this.sqlConnection1.StatisticsEnabled = true;

//

// sqlCommand1

//

this.sqlCommand1.Parameters.AddRange(new System.Data.SqlClient.SqlParameter[] {

new System.Data.SqlClient.SqlParameter("@S_ID", System.Data.SqlDbType.Int, 0, System.Data.ParameterDirection.Output, false, ((byte)(0)), ((byte)(0)), "", System.Data.DataRowVersion.Current, null),

new System.Data.SqlClient.SqlParameter("@S_NAME", System.Data.SqlDbType.VarChar),

new System.Data.SqlClient.SqlParameter("@S_ADDRESS", System.Data.SqlDbType.VarChar),

new System.Data.SqlClient.SqlParameter("@S_PHONE", System.Data.SqlDbType.Text)});

//

// sqlSelectCommand1

//

this.sqlSelectCommand1.CommandText = "SELECT S_ID, S_NAME, S_ADDRESS, S_PHONE\r\nFROM STUDENT";

this.sqlSelectCommand1.Connection = this.sqlConnection1;

//

// sqlInsertCommand1

//

this.sqlInsertCommand1.CommandText = "INSERT INTO [STUDENT] ([S_ID], [S_NAME], [S_ADDRESS], [S_PHONE]) VALUES (@S_ID, @" +

"S_NAME, @S_ADDRESS, @S_PHONE)";

this.sqlInsertCommand1.Connection = this.sqlConnection1;

this.sqlInsertCommand1.Parameters.AddRange(new System.Data.SqlClient.SqlParameter[] {

new System.Data.SqlClient.SqlParameter("@S_ID", System.Data.SqlDbType.Int, 0, "S_ID"),

new System.Data.SqlClient.SqlParameter("@S_NAME", System.Data.SqlDbType.VarChar, 0, "S_NAME"),

new System.Data.SqlClient.SqlParameter("@S_ADDRESS", System.Data.SqlDbType.VarChar, 0, "S_ADDRESS"),

new System.Data.SqlClient.SqlParameter("@S_PHONE", System.Data.SqlDbType.Text, 0, "S_PHONE")});

//

// sqlDataAdapter1

//

this.sqlDataAdapter1.InsertCommand = this.sqlInsertCommand1;

this.sqlDataAdapter1.SelectCommand = this.sqlSelectCommand1;

this.sqlDataAdapter1.TableMappings.AddRange(new System.Data.Common.DataTableMapping[] {

new System.Data.Common.DataTableMapping("Table", "STUDENT", new System.Data.Common.DataColumnMapping[] {

new System.Data.Common.DataColumnMapping("S_ID", "S_ID"),

new System.Data.Common.DataColumnMapping("S_NAME", "S_NAME"),

new System.Data.Common.DataColumnMapping("S_ADDRESS", "S_ADDRESS"),

new System.Data.Common.DataColumnMapping("S_PHONE", "S_PHONE")})});

//

// Form1

//

this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);

this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;

this.ClientSize = new System.Drawing.Size(463, 266);

this.Controls.Add(s_PHONELabel);

this.Controls.Add(this.s_PHONETextBox);

this.Controls.Add(s_ADDRESSLabel);

this.Controls.Add(this.s_ADDRESSTextBox);

this.Controls.Add(s_NAMELabel);

this.Controls.Add(this.s_NAMETextBox);

this.Controls.Add(s_IDLabel);

this.Controls.Add(this.s_IDTextBox);

this.Controls.Add(this.sTUDENTBindingNavigator);

this.Name = "Form1";

this.Text = "Form1";

this.Load += new System.EventHandler(this.Form1_Load);

((System.ComponentModel.ISupportInitialize)(this.studentDataSet)).EndInit();

((System.ComponentModel.ISupportInitialize)(this.sTUDENTBindingSource)).EndInit();

((System.ComponentModel.ISupportInitialize)(this.sTUDENTBindingNavigator)).EndInit();

this.sTUDENTBindingNavigator.ResumeLayout(false);

this.sTUDENTBindingNavigator.PerformLayout();

this.ResumeLayout(false);

this.PerformLayout();

private studentDataSet studentDataSet;

private System.Windows.Forms.BindingSource sTUDENTBindingSource;

private student.studentDataSetTableAdapters.STUDENTTableAdapter sTUDENTTableAdapter;

private System.Windows.Forms.BindingNavigator sTUDENTBindingNavigator;

private System.Windows.Forms.ToolStripButton bindingNavigatorAddNewItem;

private System.Windows.Forms.ToolStripLabel bindingNavigatorCountItem;

private System.Windows.Forms.ToolStripButton bindingNavigatorDeleteItem;

private System.Windows.Forms.ToolStripButton bindingNavigatorMoveFirstItem;

private System.Windows.Forms.ToolStripButton bindingNavigatorMovePreviousItem;

private System.Windows.Forms.ToolStripSeparator bindingNavigatorSeparator;

private System.Windows.Forms.ToolStripTextBox bindingNavigatorPositionItem;

private System.Windows.Forms.ToolStripSeparator bindingNavigatorSeparator1;

private System.Windows.Forms.ToolStripButton bindingNavigatorMoveNextItem;

private System.Windows.Forms.ToolStripButton bindingNavigatorMoveLastItem;

private System.Windows.Forms.ToolStripSeparator bindingNavigatorSeparator2;

private System.Windows.Forms.ToolStripButton sTUDENTBindingNavigatorSaveItem;

private System.Windows.Forms.TextBox s_IDTextBox;

private System.Windows.Forms.TextBox s_NAMETextBox;

private System.Windows.Forms.TextBox s_ADDRESSTextBox;

private System.Windows.Forms.TextBox s_PHONETextBox;

private System.Data.SqlClient.SqlConnection sqlConnection1;

private System.Data.SqlClient.SqlCommand sqlCommand1;

private System.Data.SqlClient.SqlCommand sqlSelectCommand1;

private System.Data.SqlClient.SqlCommand sqlInsertCommand1;

private System.Data.SqlClient.SqlDataAdapter sqlDataAdapter1;