使用vb将sql数据库连接到asp.net

Question

我在数据库名称用户（用户名，用户ID，国家）中有一个表。我想在asp.net中检索数据。但我有连接sql数据库的问题。这是我的代码

Public Sub connect() 
    Dim DatabaseName As String = "user" 
    Dim server As String = "loalhost" 
    Dim userName As String = "me" 
    Dim password As String = " " 
    If Not conn Is Nothing Then conn.Close() 
    conn.ConnectionString = String.Format("server={0}; user id={1}; password={2}; database={3}; pooling=false", server, userName, password, DatabaseName) 
End Sub 

我试试这个使用此代码，但错误检索数据

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click 
    Try 
     conn.Open() 
    Catch ex As Exception 
    End Try 
    Dim cmd As New SqlCommand(String.Format("SELECT username FROM user")) 
    cmd.ExecuteNonQuery() 
    conn.Close() 
End Sub 

Answer 1

您需要使用的ExecuteReader来获取所有数据......与ExecuteNonQuery（）用于更新数据库

  SqlCommand cmd1 = new SqlCommand(query1, con); 

      SqlDataReader reader = cmd1.ExecuteReader(); 
      //GridView2.DataSource = reader; 
      //GridView2.DataBind(); 
      while (reader.Read()) 
      { 
       String username =Convert.ToString(reader["username"]); 
       // ServicePointDetails t = new ServicePointDetails(); 
       // t.ServicePointID = Convert.ToString(reader["ServicePointID"]); 
       // t.ServicePointName = Convert.ToString(reader["ServicePointName"]); 
       // servicePointDetails_list.Add(t); 
      } 

更多信息ExecuteNonQuery

vb.net

Dim data As SqlDataReader 
Dim command As New SqlCommand 
command.CommandText = sqlquery 
command.Connection = conn 
data = cmd.ExecuteReader() 
While data.Read 
    If data.HasRows = True Then 
     Dim userName As String 
     userName = data.Item("username") 
     //Pupulate a list/do something else 
    End If 
End While 

Answer 2

我认为你的表名是不正确的：数据库是用户，什么是表名？在查询

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click 
    Try 
     conn.Open() 
    Catch ex As Exception 
    End Try 
    Dim cmd As New SqlCommand(String.Format("SELECT username FROM yourtablename")) 
    cmd.ExecuteNonQuery() 
    conn.Close() 
End Sub 

Answer 3

提供正确的表名中去除的String.Format

Dim cmd As New SqlCommand("SELECT username FROM user") 

是表名USERS不是用户？

为什么你使用String.Format作为连接字符串？

Imports System.Data 
Imports System.Data.SqlClient 
Imports System.Configuration 
... 
Dim strConnection As String = ConfigurationManager.ConnectionStrings("Something").ConnectionString 
Dim con As SqlConnection = New SqlConnection(strConnection) 

Dim da As New SqlDataAdapter("SELECT [username] FROM YourTableNameHere", con) 
ds = New DataSet 
da.Fill(ds, "MyDataTableName") 
da.Dispose() 

数据集（DS）现在包含一个用户名列表，如果在一个函数，返回结果：

Return ds