在ASP.NET中連接到SQL服務器

Question

我想從Visual Web Developer中使用asp.net連接到SQL Server，但我面臨一些問題如果有人在這方面提供幫助，我將會很有幫助。

public partial class _Default : Page 
{ 
    protected void Page_Load(object sender, EventArgs e)    
    {  
     SqlConnection conn = new SqlConnection("Server=localhost;" + "Database=DB;User ID=aaaa;" + "Password=aaaa"); 

     conn.Open(); SqlDataReader reader = conn.ExecuteReader(); 
     while (reader.Read()) { 
      employeesLabel.Text += reader["Name"] + "<br />"; 
     } 
     reader.Close(); 
     conn.Close();    
    } 
} 

我得到錯誤說

「System.Data.SqlClient.SqlConnection」不包含「的ExecuteReader」的定義，並沒有擴展方法「的ExecuteReader」接受的第一個參數可以找到類型'System.Data.SqlClient.SqlConnection'（你是否缺少使用指令或程序集引用？）

名稱'employeesLabel'不存在於curren上下文。

有人可以告訴可能的原因嗎？

Answer 1

我認爲你必須同時創建SqlCommand類的對象和命令字符串傳遞給它的構造。試試這個」

SqlConnection conn = new SqlConnection("Data Source=serverName;" 
      + "Initial Catalog=databaseName;" 
      + "Persist Security Info=True;" 
      + "User ID=userName;Password=password"); 

conn.Open(); 

// create a SqlCommand object for this connection 
SqlCommand command = conn.CreateCommand(); 
command.CommandText = "Select * from tableName"; 
command.CommandType = CommandType.Text; 

// execute the command that returns a SqlDataReader 
SqlDataReader reader = command.ExecuteReader(); 

// display the results 
while (reader.Read()) { 
    //whatever you want to do. 
} 

// close the connection 
reader.Close(); 
conn.Close(); 

Answer 2

糟糕！只有IDbCommand的實現具有的ExecuteReader全部退回的DataReader：

• http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlcommand.aspx

Answer 3

您沒有傳遞任何命令/查詢的ExecuteReader這樣的事情是正確的：

SqlDataReader rdr = null; 
conn.Open(); 
SqlCommand cmd = new SqlCommand("select * from Customers", conn); 
rdr = cmd.ExecuteReader(); 

Answer 4

嘗試

SqlConnection conn = new SqlConnection("Server=localhost;" + "Database=DB;User ID=aaaa;" + "Password=aaaa");    
conn.Open(); 
SqlCommand cmd = new SqlCommand("Your Query", conn);//Put your query here 
SqlDataReader reader = cmd.ExecuteReader();    
while (reader.Read()) 
{     
    employeesLabel.Text += reader["Name"] + "<br />"; 
} 
reader.Close();    
conn.Close(); 

Answer 5

using (SqlConnection conn = new SqlConnection(...)) 
using (SqlCommand command = conn.CreateCommand()) 
{ 
    command.CommandText = "..."; 
    conn.Open(); 
    using (SqlDataReader reader = command.ExecuteReader()) 
    { 
     // do the sutff 
    } 
} 

Answer 6

SqlConnection沒有任何ExecuteReader（）方法。 您必須創建SqlCommand的對象。 您的代碼應該是這樣的：

namespace LearningASP 

{ public partial class _Default : System.Web.UI.Page 

{ protected void Page_Load(object sender, EventArgs e) 

{ 

SqlConnection conn = new SqlConnection("Server=localhost;" + "Database=DB;User ID=aaaa;" + "Password=aaaa"); 

     conn.Open(); 
**SqlCommand cmd = new SqlCommand(); 
     SqlDataReader reader = cmd.ExecuteReader();** 
while (reader.Read()) {    employeesLabel.Text += reader["Name"] + "<br />"; } reader.Close();   conn.Close();  } } }