Question

我正在使用Visual Studio 2015和SQL Server 2014.问题基于C＃。

这是一个库存盘点系统。我有两种形式：

股票报名表（它有SAVE，UPDATE，DELETE按钮）
股票gridview表单

我可以保存没有图像的库存条目这个过程有效，如果我需要更新，我将点击单元格双击Stock gridview表格，然后股票条目表格将打开所有条目，然后我可以进行更改并且更新但没有图像我无法更新该问题。

我更新现有记录时出现的错误，该记录确实有图像，我正在进行更改并再次更新没有图像，然后弹出此错误：

对象引用未设置为对象的实例

这是通过SAVE按钮代码：工作正常，这意味着我可以保存没有图像：

private void btnsave_Click(object sender, EventArgs e)
{
        try
        {
            conn.Close();
            conn.Open();

            String query;

            if (pb1.Image == null)
            {
                query = "INSERT INTO Stock_Gems (Stock_Type, Stock_no, No_of_pieces, Gem_Type, Weight, Cost, Create_Date, Update_Date, UserID) VALUES (@Stock_Type, @stock_no, @No_of_pieces, @Gem_Type, @Weight, @Cost, @Created_Date, @Updated_Date, @User_Create)";
            }
            else
            {
                query = "INSERT INTO Stock_Gems VALUES(@Stock_Type, @stock_no, @No_of_pieces, @Gem_Type, @Weight, @image, @Cost, @Created_Date, @Updated_Date, @User_Create)";
            }
            SqlCommand command = new SqlCommand(query, conn);

            command.Parameters.Add("@Stock_Type", SqlDbType.VarChar);
            command.Parameters["@Stock_Type"].Value = Stock_Type.Text;

            command.Parameters.Add("@stock_no", SqlDbType.VarChar);
            command.Parameters["@stock_no"].Value = txtstock_no.Text;

            command.Parameters.Add("@No_of_pieces", SqlDbType.Int);
            command.Parameters["@No_of_pieces"].Value = txtno_of_peices.Text;

            command.Parameters.Add("@Gem_Type", SqlDbType.NVarChar);
            command.Parameters["@Gem_Type"].Value = txt_gems.Text;

            command.Parameters.Add("@Weight", SqlDbType.Float);
            command.Parameters["@Weight"].Value = txt_weight.Text;

            if (pb1.Image != null)
            {
                MemoryStream stream = new MemoryStream();
                pb1.Image.Save(stream, System.Drawing.Imaging.ImageFormat.Jpeg);
                byte[] pic = stream.ToArray();
                command.Parameters.Add("@image", SqlDbType.Binary);
                command.Parameters["@image"].Value = pic;
            }

            command.Parameters.Add("@Cost", SqlDbType.Decimal);
            command.Parameters["@Cost"].Value = txt_cost.Text;
            command.Parameters.Add("@Created_Date", SqlDbType.DateTime);
            command.Parameters["@Created_Date"].Value = label11.Text;
            command.Parameters.Add("@Updated_Date", SqlDbType.DateTime);
            command.Parameters["@Updated_Date"].Value = label11.Text;
            command.Parameters.Add("@User_Create", SqlDbType.NVarChar);
            command.Parameters["@User_Create"].Value = hello.Text;

            command.ExecuteNonQuery();
            conn.Close();

            if (cmbStockType.SelectedIndex == 0)
                _lastUG++;
            else
                _lastMG++;
            saveLastNumbers();
            MessageBox.Show("You've inserted successfully!", "Successful Message", MessageBoxButtons.OK, MessageBoxIcon.Information);
            this.Hide();
        }

        catch (Exception ex)
        {
            MessageBox.Show(ex.Message, "Error Message", MessageBoxButtons.OK, MessageBoxIcon.Error);
        }
}

这是我的UPDATE按钮代码：

private void btnupdate_Click(object sender, EventArgs e)
{
        try
        {
            conn.Close();
            conn.Open();

            SqlCommand command = new SqlCommand("Update Stock_Gems  set Stock_Type = @Stock_Type, Stock_No = @Stock_No , No_of_pieces = @No_of_pieces, Gem_Type = @Gem_Type, Weight = @Weight, Image = @Image, Cost = @Cost, Update_Date = @Update_Date  WHERE  Stock_No = @Stock_No", conn);

            //command.Parameters.Add("@ID", SqlDbType.Int).Value = txt_ID.Text;
            command.Parameters.Add("@Stock_Type", SqlDbType.VarChar).Value = Stock_Type.Text;
            command.Parameters.Add("@stock_no", SqlDbType.NVarChar).Value = txtstock_no.Text;
            command.Parameters.Add("@No_of_pieces", SqlDbType.Int).Value = txtno_of_peices.Text;
            command.Parameters.Add("@Gem_Type", SqlDbType.NVarChar).Value = txt_gems.Text;
            command.Parameters.Add("@Weight", SqlDbType.Float).Value = txt_weight.Text;

            using (MemoryStream ms = new MemoryStream())
            {
                pb1.Image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
                command.Parameters.Add("@Image", SqlDbType.Image).Value = ms.ToArray();
            }
            command.Parameters.Add("@Cost", SqlDbType.Decimal).Value = txt_cost.Text;
            command.Parameters.Add("@Update_Date", SqlDbType.DateTime).Value = label11.Text;
            command.ExecuteNonQuery();

            if (cmbStockType.SelectedIndex == 0)
                _lastUG++;
            else
                _lastMG++;
            saveLastNumbers();

            MessageBox.Show("You've updated successfully!", "Successful Message", MessageBoxButtons.OK, MessageBoxIcon.Information);
            conn.Close();
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message, "Error Message", MessageBoxButtons.OK, MessageBoxIcon.Error);
        }
        conn.Close();
        this.Close();
}

这是我的gridview单元格双击代码：

private void dataGridView1_CellDoubleClick(object sender, DataGridViewCellEventArgs e)
{
        S_Gems myForm = new S_Gems();
        myForm.Stock_Type.Text = this.dataGridView1.CurrentRow.Cells[1].Value.ToString();
        myForm.txtstock_no.Text = this.dataGridView1.CurrentRow.Cells[2].Value.ToString();
        myForm.txtno_of_peices.Text = this.dataGridView1.CurrentRow.Cells[3].Value.ToString();
        myForm.txt_gems.Text = this.dataGridView1.CurrentRow.Cells[4].Value.ToString();
        myForm.txt_weight.Text = this.dataGridView1.CurrentRow.Cells[5].Value.ToString();

        byte[] pic = this.dataGridView1.CurrentRow.Cells[6].Value as byte[];

        if (pic != null)
        {
            MemoryStream stream = new MemoryStream(pic);
            myForm.pb1.Image = Image.FromStream(stream);
        }
        else
            myForm.pb1.Image = null;

        myForm.txt_cost.Text = this.dataGridView1.CurrentRow.Cells[7].Value.ToString();
        //  myForm.hello.Text = this.dataGridView1.CurrentRow.Cells[10].Value.ToString();
        myForm.ShowDialog();
}

我不知道从哪里得到这些错误请帮助

不允许将null映像更新到数据库：UPDATE进程发生时显示错误c＃

0 个答案: