无法从 sqldatareader 读取多行

Question

当我只查询一个记录/行时，sqldatareader 给出正确的结果，但是当我查询多行时，它在客户端给出错误。下面是我的代码。请告诉我这里有什么问题。

   [WebMethod]
    public static string SendMessage(string order)
    {
            string Server = "alyeyey";
            string Username = "apjsjsjs";
            string Password = "jjsjsjs";
            string Database = "Amhshshs";

            string ConnectionString = "Data Source=" + Server + ";";
            ConnectionString += "User ID=" + Username + ";";
            ConnectionString += "Password=" + Password + ";";
            ConnectionString += "Initial Catalog=" + Database;
            string query = "select * from optionsRelation where orderNumber = " + order;//+" OR orderNumber = 17";

            DataTable dt = new DataTable();

            Hashtable sendData = new Hashtable();

        try
            {
            using (SqlConnection conn = new SqlConnection(ConnectionString))
            {
                using (SqlCommand cmd = new SqlCommand(query, conn))
                {
                    conn.Open();
                    SqlDataReader dr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
                    dt.Load(dr);
                }
            }

            //Creating StringBuilder array for storing keys
            StringBuilder[] empKeys = new StringBuilder[4];

            for (int i = 0; i < empKeys.Length; i++)
            {
                empKeys[i] = new StringBuilder();
            }

            //Creating stringbuilder array for storing key values
            StringBuilder[] empDetails = new StringBuilder[4];

            for (int i = 0; i < empDetails.Length; i++)
            {
                empDetails[i] = new StringBuilder();
            }

            //putting datatable data to Keys array i-e empKeys and Values array i-e empDetails array
            int inc = 0;
            int j = 0;
            foreach (DataRow dr in dt.Rows)
            {
                foreach (DataColumn dc in dt.Columns)
                {
                    empKeys[inc].Append(dc.ColumnName);
                    inc++;
                }
                foreach (DataColumn dc in dt.Columns)
                {
                    empDetails[j].Append(dr[dc]);
                    j++;
                }
            }

            //mapping keys array and values array in hashtable

            for (int k = 0; k < empKeys.Length; k++)
            {
                sendData.Add(empKeys[k].ToString(), empDetails[k].ToString());
            }
            //sendData.Add("orderNum", order);
            JavaScriptSerializer jss = new JavaScriptSerializer();
            string output = jss.Serialize(sendData);
            return output;
        }
        catch (Exception ex)
        {
            return ex.Message + "-" + ex.StackTrace;
        }
    }
}

Answer 1

这样的？但是，这并不能解决您的客户端错误。它确实使用参数而不是字符串连接。

    string query = "select * from Customer_Order where orderNumber = @ordernumber";

    DataTable dt = new DataTable();

    using (SqlConnection conn = new SqlConnection(ConnectionString))
    {
        using (SqlCommand cmd = new SqlCommand(query, conn))
        {
            cmd.Parameters.Add(new SqlParameter("ordernumber", ordernumber));
            SqlDataAdapter dr = new SqlDataAdapter(cmd);
            dr.Fill(dt);
        }
    }

Answer 2

客户端发生错误，但这是因为数据来自服务器端。因为我已经检查了向该客户端发送不同的值，并且这些值可以正常工作。即使我只对一行使用查询字符串，例如“从 orderNumber = 17 的表中选择 *”，它也可以正常工作。但在查询多行时出错。并且“order”是从jquery ajax调用传递的字符串参数（我已经检查过“order”是否包含正确的字符串，所以没有问题）。我正在使用 empKeys 和 empDetails 数组来保存数据表值以将它们转换为哈希表，因为我必须将 json 格式的数据发送到 javascript 并且只有使用哈希表才能成功地做到这一点。以下是我的整个服务器端代码：

    using System.Web.UI.WebControls;
using System.Web.Services;
using System.Data;
using System.Text;
using System.Web.Script.Serialization;
using System.Web.Script.Services;
using System.Collections;
using System.Data.SqlClient;

public partial class orderSearch : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e){}


    [WebMethod]
    public static string SendMessage(string order)
    {
            string Server = "alyeyey";
            string Username = "apjsjsjs";
            string Password = "jjsjsjs";
            string Database = "Amhshshs";

            string ConnectionString = "Data Source=" + Server + ";";
            ConnectionString += "User ID=" + Username + ";";
            ConnectionString += "Password=" + Password + ";";
            ConnectionString += "Initial Catalog=" + Database;
            string query = "select * from optionsRelation where orderNumber = " + order;//+" OR orderNumber = 17";

            DataTable dt = new DataTable();

            Hashtable sendData = new Hashtable();

        try
            {
            using (SqlConnection conn = new SqlConnection(ConnectionString))
            {
                using (SqlCommand cmd = new SqlCommand(query, conn))
                {
                    conn.Open();
                    SqlDataReader dr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
                    dt.Load(dr);
                }
            }

            //Creating StringBuilder array for storing keys
            StringBuilder[] empKeys = new StringBuilder[4];

            for (int i = 0; i < empKeys.Length; i++)
            {
                empKeys[i] = new StringBuilder();
            }

            //Creating stringbuilder array for storing key values
            StringBuilder[] empDetails = new StringBuilder[4];

            for (int i = 0; i < empDetails.Length; i++)
            {
                empDetails[i] = new StringBuilder();
            }

            //putting datatable data to Keys array i-e empKeys and Values array i-e empDetails array
            int inc = 0;
            int j = 0;
            foreach (DataRow dr in dt.Rows)
            {
                foreach (DataColumn dc in dt.Columns)
                {
                    empKeys[inc].Append(dc.ColumnName);
                    inc++;
                }
                foreach (DataColumn dc in dt.Columns)
                {
                    empDetails[j].Append(dr[dc]);
                    j++;
                }
            }

            //mapping keys array and values array in hashtable

            for (int k = 0; k < empKeys.Length; k++)
            {
                sendData.Add(empKeys[k].ToString(), empDetails[k].ToString());
            }
            //sendData.Add("orderNum", order);
            JavaScriptSerializer jss = new JavaScriptSerializer();
            string output = jss.Serialize(sendData);
            return output;
        }
        catch (Exception ex)
        {
            return ex.Message + "-" + ex.StackTrace;
        }
    }
}

Answer 3

试试这个...我认为这仍然有错误的 JSON 输出，但它会给你这个想法。请参阅 Rick Strahl 在converting a datatable to json 上的文章。这比我的例子复杂一点。

            List<Hashtable> sendData = new List<Hashtable>();

            foreach (DataRow dr in dt.Rows)
            {
                foreach (DataColumn dc in dt.Columns)
                {
                    Hashtable ht = new Hashtable();
                    ht.Add(dc.ColumnName, dr[dc].ToString());
                    sendData.Add(ht);
                }
            }