使用sqlserver从sqldatareader获取数据 [英] getting data from sqldatareader using sqlserver

问题描述

大家好，

我是C＃的新手。我试图使用返回类型为'SqlDataReader'的函数填充datareader但不幸的是它给出了一些错误。任何建议都会非常感激。

谢谢，

Akky

Hi guys,
I am new to C#. I am trying to fill a datareader using a function with return type as 'SqlDataReader' but unfortunately its giving some error. Any advice would be really appreciated.
Thanks,
Akky

public static void Main(string[] args)
       {

           SqlDataReader dr = Program.hello("select top 10 firstName,lastName from DimCustomer");
           while (dr.Read())
           {
               Console.WriteLine(dr.GetValue(0));
           }
           Console.ReadLine();

       }
       public static SqlDataReader hello(string query)
       {
           SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=adventure_works;Integrated Security=true;");
           SqlCommand cmd = new SqlCommand(query, con);
           con.Open();
           SqlDataReader dr = cmd.ExecuteReader();
           con.Close();
           return dr;
       }

推荐答案

只需从con.Close（）代码中删除一行，因为SqlDataReader可以在连接模式，它只读取前进模式。

Just remove one line from code that is con.Close() because SqlDataReader works in connected mode and it read forward only mode.

using System;
using System.Data.SqlClient;

namespace RestApp
{
    class Program
    {
        public static void Main(string[] args)
        {

            SqlDataReader dr = Program.hello("select top 10 firstName,lastName from DimCustomer");
            while (dr.Read())
            {
                Console.WriteLine(dr.GetValue(0));
            }
            Console.ReadLine();

        }
        public static SqlDataReader hello(string query)
        {
            SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=adventure_works;Integrated Security=true;");
            SqlCommand cmd = new SqlCommand(query, con);
            con.Open();
            SqlDataReader dr = cmd.ExecuteReader();
            con.Close();
            return dr;
        }
    }
    
  
}

class Program
{
    static SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=adventure_works;Integrated Security=true;");
    public static void Main(string[] args)
    {

        SqlDataReader dr = Program.hello("select top 10 firstName,lastName from DimCustomer");
        while (dr.Read())
        {
            Console.WriteLine(dr.GetValue(0));
        }
        con.Close();
        Console.ReadLine();

    }
    public static SqlDataReader hello(string query)
    {
        
        SqlCommand cmd = new SqlCommand(query, con);
        con.Open();
        SqlDataReader dr = cmd.ExecuteReader(); 
  con.Close();
        return dr;

    }
}

您应该添加一些代码来处理行，如下所示

You should add some code to process rows as follows

while (reader.Read())
{
 
      // Do something with rows
     for( int i = 0; i < reader.FieldCount; i++ ){
     }
//... or
     string field = (string)reader["column1"];
}

详情请参阅这些链接



SqlCommand.ExecuteReader方法 [ ^ ]



SqlDataReader 。阅读 [ ^ ]

这篇关于使用sqlserver从sqldatareader获取数据的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！