Question

我正在創建一個將csv文件讀入C＃中的數據網格視圖的應用程序。該文件由項目編號和庫存等數據組成。

如果料號相同，則應添加其庫存，然後用相同料號替換數據庫中的當前庫存。

我能夠從csv文件添加庫存到數據庫中的相同商品編號的數據庫，但我無法替換庫存。

這裏是我的代碼：

string sql_select = "select count(*) from PRODUCTS where item_no= '" + 
          itemNo + "'"; 
    SqlCommand cmdCheckPmk = new SqlCommand(sql_select, Class1.conn); 

    int selectItemNo = Convert.ToInt32(cmdCheckPmk.ExecuteScalar()); 

    if (selectItemNo != 0) 
    { 
     string sql_update = "update PRODUCTS set item_stock=+'" + Stock + 
          "' where item_no= '" + itemNo + "'"; 
     SqlCommand cmd1 = new SqlCommand(sql_update, Class1.conn); 
    } 
    else 
    { 
     SqlCommand cmd11 = new SqlCommand("insert into PRODUCTS(item_no,item_name,price,cost,item_stock,dept_id,tax_rate1,tax_rate2,bulk_price,bulk_qty) values ('" + itemNo + "','" + itemName + "'," + price + "," + cost + "," + Stock + ",'" + dept + "','" + tax1 + "','" + tax2 + "'," + BulkPrize +"," + BulkQty +") ", Class1.conn); 
     cmd11.ExecuteNonQuery(); 
    } 

我使用SQL Server 2008 R2。

Answer 1

你上面的例子有很多小問題。

研究下面的基本示例作爲更好的方法。

// Pass in your SQL Connection object so you do not have to worry about 
// multiple open connections 
public int jp2Test(SqlConnection conn) { 
    // Verify someone did not pass in a NULL object 
    if (conn != null) { 
    string sql_text = "select count(*) from PRODUCTS where item_no=@item_no"; 
    using (SqlCommand cmd = new SqlCommand(sql_text, conn)) { 
     // Get in the habit of using Parameters. If you know the SqlDbType, use one of 
     // the Parameter overloads that provides for this. 
     cmd.Parameters.AddWithValue("@item_no", itemNo); 
     // Open the connection if it is not already 
     if ((cmd.Connection.State & ConnectionState.Open) != ConnectionState.Open) { 
     cmd.Connection.Open(); 
     } 
     // initialize an item_number variable 
     int selectedItemNo = -1; 
     object value = cmd.ExecuteScalar(); 
     // Check for both NULL and DBNull 
     if ((value != null) && (value != DBNull.Value)) { 
     selectedItemNo = Convert.ToInt32(value); 
     } 
     // Update your SQL Text based on the value you received. 
     if (0 < selectedItemNo) { 
     sql_text = "update PRODUCTS set item_stock=@item_stock where item_no=@item_no"; 
     // this value is already included 
     // cmd.Parameters.AddWithValue("@item_no", itemNo); 
     // this is a common value that will be added after the conditional 
     // cmd.Parameters.AddWithValue("@item_stock", Stock); 
     } else { 
     sql_text = "insert into PRODUCTS" + 
      " (item_no, item_name, price, cost, item_stock, dept_id, tax_rate1, tax_rate2, bulk_price, bulk_qty)" + 
      " values " + 
      "(@item_no,@item_name,@price,@cost,@item_stock,@dept_id,@tax_rate1,@tax_rate2,@bulk_price,@bulk_qty)"; 
     // this value is already included 
     // cmd.Parameters.AddWithValue("@item_no", itemNo); 
     cmd.Parameters.AddWithValue("@item_name", itemName); 
     cmd.Parameters.AddWithValue("@price", price); 
     cmd.Parameters.AddWithValue("@cost", cost); 
     // this is a common value that will be added after the conditional 
     // cmd.Parameters.AddWithValue("@item_stock", Stock); 
     cmd.Parameters.AddWithValue("@dept_id", dept); 
     cmd.Parameters.AddWithValue("@tax_rate1", tax1); 
     cmd.Parameters.AddWithValue("@tax_rate2", tax2); 
     cmd.Parameters.AddWithValue("@bulk_price", BulkPrize); 
     cmd.Parameters.AddWithValue("@bulk_qty", BulkQty); 
     } 
     cmd.CommandText = sql_text; 
     cmd.Parameters.AddWithValue("@item_stock", Stock); 
     // Return the number of SQL records that were affected. 
     return cmd.ExecuteNonQuery(); 
    } 
    } 
    // return -1 on Error 
    return -1; 
}