Storing a value from SQL database to a variable

I tried this code to extract a single value from my database and store it in a variable. But it extracts the value Supplier ID instead of Quantity.

string query3 = "SELECT Quantity FROM Supplier WHERE [Supplier ID]='"+supplierid+"'";
SqlCommand cmd3 = new SqlCommand(query3, con);
con.Open();
string temporaryquantity = cmd.ExecuteScalar().ToString();
MessageBox.Show(temporaryquantity);

How can I extract Quantity instead of Supplier ID?

#c-sharp #sql #database