错误：找不到表0

Question

 con.Open();
 SqlDataAdapter da4 = new SqlDataAdapter("select * from tblbooking where bookid =(select max(bookid) from tblbooking)", con);
 DataSet ds4 = new DataSet();
 pay = ds4.Tables[0].Rows[0]["costoftickets"].ToString();
 Label4.Text = "Amount to Pay : " + pay + " INR.";
 da4.Fill(ds4);
 DetailsView1.DataSource = ds4;
 DetailsView1.DataBind();
 con.Close();

Answer 1

在访问其内容之前，您尚未填充DataSet，因此当然没有数据。

con.Open(); 
SqlDataAdapter da4 = new SqlDataAdapter("select * from tblbooking where bookid =(select max(bookid) from tblbooking)", con); 
DataSet ds4 = new DataSet(); 
da4.Fill(ds4); // this needs to go before accessing the data
pay = ds4.Tables[0].Rows[0]["costoftickets"].ToString(); 
Label4.Text = "Amount to Pay : " + pay + " INR."; 
DetailsView1.DataSource = ds4; 
DetailsView1.DataBind(); 
con.Close();

请注意，如果查询未返回任何数据，您仍可能会收到错误。