Insert SQL statement is not working after checking against quantities from tables in database - sql

Question

I created a sale table which Insert function does not work properly. It shows the error message
Must declare the scalar variable "#iProductID"
at the statement
using (var sdRead = cmdOrder.ExecuteReader())
I am really stuck here. I also want to know how I can achieve for inserting SaleID with auto-increment without with any input field at the form. Every time I insert a new record, SaleID should be auto-generated and saved in the database.
My code below work like this. I checked available stocks from my Product table. If quantity order is greater than quantity from Product table, show error message.
Otherwise, proceed to inserting order information into Sale table. Any help is appreciated.
private void btnOrder_Click(object sender, EventArgs e)
{
int iQuantityDB;
int iCustomerID = Convert.ToInt32(txtCustomerID.Text);
int iProductID = Convert.ToInt32(txtProductID.Text);
decimal dPrice = Convert.ToDecimal(txtPrice.Text);
int iQuantity = Convert.ToInt32(txtQuantity.Text);
decimal dSubtotal = Convert.ToDecimal(txtSubTotal.Text);
decimal dGST = Convert.ToDecimal(txtGST.Text);
decimal dTotal = Convert.ToDecimal(txtTotal.Text);
string strConnectionString = #"Data Source = KK\SQLEXPRESS; Integrated Security = SSPI; Initial Catalog = JeanDB; MultipleActiveResultSets=True;";
using (var sqlconn = new SqlConnection(strConnectionString))
{
sqlconn.Open();
string querySelectQuantity = #"Select Quantity from dbo.JeanProduct WHERE ProductID = #iProductID";
using (var cmdOrder = new SqlCommand(querySelectQuantity, sqlconn))
{
using (var sdRead = cmdOrder.ExecuteReader())
{
sdRead.Read();
iQuantityDB = Convert.ToInt32(sdRead["Quantity"]);
}
}
if (iQuantityDB > iQuantity)
{
string InsertQuery = #"INSERT INTO Sale(CustomerID, ProductID, Price, Quantity, Subtotal, GST, Total)VALUES(#iCustomerID, #iProductID, #dPrice, #iQuantity, #dSubtotal, #dGST, #Total)";
using (var InsertCMD = new SqlCommand(InsertQuery, sqlconn))
{
InsertCMD.Connection = sqlconn;
InsertCMD.Parameters.AddWithValue("#iCustomerID", iCustomerID);
InsertCMD.Parameters.AddWithValue("#iProdcutID", iProductID);
InsertCMD.Parameters.AddWithValue("#dPrice", dPrice);
InsertCMD.Parameters.AddWithValue("#iQuantity", iQuantity);
InsertCMD.Parameters.AddWithValue("#dSubtotal", dSubtotal);
InsertCMD.Parameters.AddWithValue("#dGST", dGST);
InsertCMD.Parameters.AddWithValue("#dTotal", dTotal);
InsertCMD.ExecuteNonQuery();
LoadDataonTable();
}
}
else
{
MessageBox.Show("no more stock");
}
sqlconn.Close();
}
}

Answer 1

At the line using (var sdRead = cmdOrder.ExecuteReader()) your SQL SELECT query is using a parameter - WHERE ProductID = #iProductID - but this hasn't been set. Hence the error message Must declare the scalar variable "#iProductID"
Just add cmdOrder.Parameters.AddWithValue("#iProductID", iProductID) between defining the SQL and executing it, and that should clear that problem.
Moving on to the next one - you're using AddWithValue("#dTotal" but it's #Total in the SQL :)