Error converting data type varchar to numeric

Question

My Code is that and How to remove this error?

 

//New Insert / New Entry

if (lblItemcode.Text == "-")

{

string imageName = pid + lblFileExtension.Text;

string sql1 = " insert into purchase (product_id, product_name, product_quantity, cost_price, retail_price, total_cost_price, " +

" total_retail_price, category, supplier , imagename, discount, taxapply, Shopid , status, brand, generic, expiry_date, discount_allowed) " +

" values ('" + pid + "', '" + pname + "', '" + quan + "', '" + cprice + "', '" + sprice + "', '" + ctotalpri + "', " +

" '" + rtotalpri + "', '" + ComboCategory.Text + "', '" + cmbSupplier.Text + "' , '" + imageName + "', " +

" '" + discount + "' , '" + taxapply + "' , '" + cmboShopid.SelectedValue + "' , '"+ kitchenDisplaythisitem + "', '" + comboBrand.Text + "', '" + comboGeneric.Text + "', '" + dateTimePicker1.Text + "', '" + txtdiscountallowed + "')";

DataAccess.ExecuteSQL(sql1);

//Add to purchase history - New item history

insertpurchasehistory("NEW", quan, DateTime.Now.ToString("yyyy-MM-dd"));

//picture upload /////////////////

// if (openFileDialog1.FileName != string.Empty)

// {

string path = Application.StartupPath + @"\ITEMIMAGE\";

System.IO.File.Delete(path + @"\" + imageName);

if (!System.IO.Directory.Exists(path))

System.IO.Directory.CreateDirectory(Application.StartupPath + @"\ITEMIMAGE\");

string filename = path + @"\" + openFileDialog1.SafeFileName;

picItemimage.Image.Save(filename, System.Drawing.Imaging.ImageFormat.Png);

System.IO.File.Move(path + @"\" + openFileDialog1.SafeFileName, path + @"\" + imageName);

// }

MessageBox.Show("Item hase been saved Successfully", "Successful", MessageBoxButtons.OK, MessageBoxIcon.Information);

if (UserInfo.usertype == "1")

{

Stock_List go = new Stock_List();

go.MdiParent = this.ParentForm;

go.Show();

this.Close();

}

else

{

// btnItemLink.Visible = false;

}

// ClearForm();

}

else //Update

{

string imageName;

if (lblFileExtension.Text == "item.png") //if not select image

{

imageName = lblimagename.Text;

}

else // select image

{

imageName = lblItemcode.Text + lblFileExtension.Text;

}

string sql =" update purchase set product_name = '" + txtProductName.Text + "', product_quantity= '" + txtProductQty.Text + "', " +

" cost_price = '" + txtCostPrice.Text + "', retail_price= '" + txtSalesPrice.Text + "', total_cost_price = '" + ctotalpri + "', " +

" total_retail_price= '" + rtotalpri + "', category = '" + ComboCategory.Text + "', supplier = '" + cmbSupplier.Text + "', " +

" imagename = '" + imageName + "' , discount = '" + discount + "' , taxapply = '" + taxapply + "' , " +

" Shopid = '" + cmboShopid.SelectedValue + "', brand = '" + comboBrand.Text + "', generic = '" + comboGeneric.Text + "', expiry_date = '" + dateTimePicker1.Text + "', discount_allowed = '" + txtdiscountallowed + "' , status = '" + kitchenDisplaythisitem + "' " +

" where product_id = '" + lblItemcode.Text + "'";

DataAccess.ExecuteSQL(sql);

/////////////////////////////////////////////Update image //////////////////////////////////////////////////////

if (lblFileExtension.Text != "item.png") // if select image

{

picItemimage.InitialImage.Dispose();

string path = Application.StartupPath + @"\ITEMIMAGE\";

System.IO.File.Delete(path + @"\" + lblimagename.Text);

if (!System.IO.Directory.Exists(path))

System.IO.Directory.CreateDirectory(Application.StartupPath + @"\ITEMIMAGE\");

string filename = path + @"\" + openFileDialog1.SafeFileName;

picItemimage.Image.Save(filename, System.Drawing.Imaging.ImageFormat.Png);

System.IO.File.Move(path + @"\" + openFileDialog1.SafeFileName, path + @"\" + imageName);

}

MessageBox.Show("Successfully Data Updated!", "Successful", MessageBoxButtons.OK, MessageBoxIcon.Information);

//loadData();

if (UserInfo.usertype == "1")

{

Stock_List go = new Stock_List();

go.MdiParent = this.ParentForm;

go.Show();

this.Close();

}

else

{

// btnItemLink.Visible = false;

}

}

}

catch (Exception exp)

{

MessageBox.Show("Sorry\r\n this id already added \n" + exp.Message);

}

}

//this.Hide();

}