我正在建立一個電子商務網站，我使用數據列表來顯示我的產品，當我按下“添加到購物車”按鈕時，它們應該被添加到數據庫表中，但由于某種原因，產品沒有被在數據庫表中更新。此外，單擊第一個產品會出現錯誤，提示“已經有一個打開的閱讀器”，顯示錯誤的行是“int result = comm.ExecuteNonQuery();”using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;using System.Data;using System.Data.SqlClient;using System.Configuration;using System.Globalization;namespace MWM1812{ public partial class productCatalog : System.Web.UI.Page { public enum MessageType { Success, Error, Info, Warning }; protected void ShowMessage(string Message, MessageType type) { ScriptManager.RegisterStartupScript(this, this.GetType(), System.Guid.NewGuid().ToString(), "ShowMessage('" + Message + "','" + type + "');", true); } protected void Page_Load(object sender, EventArgs e) { } protected void DataList1_SelectedIndexChanged(object sender, EventArgs e) { } protected void DataList1_ItemCommand(object source, DataListCommandEventArgs e) { if (e.CommandName == "AddToCart") { Session["uid"] = 1; Label lbl = (Label)e.Item.FindControl("PIDLabel"); lblAtC.Text = lbl.Text; ShowMessage("Product successfully added to Cart", MessageType.Success); string connStr = ConfigurationManager.ConnectionStrings["MWM1812ConnString"].ConnectionString; SqlConnection conn = new SqlConnection(connStr); conn.Open(); string sqlQuery = "SELECT * FROM tblShoppingCart WHERE uid=@uid AND pid=@pid"; SqlCommand comm = new SqlCommand(sqlQuery, conn); comm.Parameters.AddWithValue("@uid", Session["uid"]); comm.Parameters.AddWithValue("@pid", lblAtC.Text.Trim()); } } } } }}
1 回答
蕭十郎
TA貢獻1815條經驗 獲得超13個贊
嘗試像這樣更新代碼：
if (e.CommandName == "AddToCart") {
bool productExists = false;
Session["uid"] = 1;
Label lbl = (Label) e.Item.FindControl("PIDLabel");
lblAtC.Text = lbl.Text;
ShowMessage("Product successfully added to Cart", MessageType.Success);
string connStr = ConfigurationManager.ConnectionStrings["MWM1812ConnString"].ConnectionString;
SqlConnection conn = new SqlConnection(connStr);
conn.Open();
string sqlQuery = "SELECT * FROM tblShoppingCart WHERE uid=@uid AND pid=@pid";
SqlCommand comm = new SqlCommand(sqlQuery, conn);
comm.Parameters.AddWithValue("@uid", Session["uid"]);
comm.Parameters.AddWithValue("@pid", lblAtC.Text.Trim());
using(SqlDataReader reader = comm.ExecuteReader()) {
productExists = reader.HasRows;
}
if (productExists) {
string sqlQuery2 = "UPDATE tblShoppingCart SET qty=qty+1 WHERE uid=@uid AND pid=@pid";
// Add code for adding parameters and executing sqlQuery2
} else {
string sqlQuery1 = "INSERT INTO tblShoppingCart (uid, pid, qty, dtShopped) VALUES (@uid, @pid, @qty, @dtShopped)";
SqlCommand comma = new SqlCommand(sqlQuery, conn);
comma.Parameters.AddWithValue("@uid", Session["uid"]);
comma.Parameters.AddWithValue("@pid", lblAtC.Text);
comma.Parameters.AddWithValue("@qty", 1);
//comm.Parameters.AddWithValue("@dtShopped", DateTime.Now.ToLongDateString());
comma.Parameters.AddWithValue("@dtShopped", DateTime.Now.ToString());
int result = comma.ExecuteNonQuery();
}
}
注意使用 reader.HasRows 屬性來確定產品是否已經存在。此外，SqlDataReader 被包裝在using塊內以將其處理掉。
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