使用 Visual Basic 连接到数据库

Question

我正在尝试连接一个数据库，但它崩溃了，它说有一个 连接问题，我已经在其他PC上尝试过此代码，但现在不起作用 错误是：

There was a network or instance-specific error while trying to establish a connection to SQL Server. The server was not found or is not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections.

代码是这样的：

Module Module1
'FUNZIONE PER LA CONNESSIONE AL DATABASE
Public Function Connetti(ByVal sql As String, ByVal namedset As String, ByRef dataSet As DataSet)
    Dim myConnString As String = "Persist Security Info=False;database=test;server=95.134.229.235;user id=web;pwd=fiautoppzione" 'server=Server206 'user id=utente_std;pwd=145111
    Dim myConnection As New SqlConnection(myConnString)
    Dim myInsertQuery As String = sql
    Dim myCommand As New SqlCommand(myInsertQuery)
    Dim myada As New SqlDataAdapter
    Dim mydset As New DataSet(namedset)
    Dim mydbs As New BindingSource
    'IO.File.AppendAllText("C:aggiorna.txt", sql & vbCrLf)
    myCommand.Connection = myConnection
    myada.SelectCommand = myCommand
    myada.MissingSchemaAction = MissingSchemaAction.AddWithKey
    mydset.EnforceConstraints = False
    mydset.Clear()
    myada.Fill(mydset, namedset)
    mydbs.DataSource = mydset.Tables(namedset)
    If Mid(sql, 1, 6) = "update" Then
        mydset.Clear()
        myada.Fill(mydset, namedset)
        mydbs.DataSource = mydset.Tables(namedset)
    End If
    myConnection.Open()
    dataSet = mydset
    myCommand.Connection.Close()
    Return mydbs
End Function

和代码的第一部分：

Option Explicit On
Imports System.Data
Imports System.Data.Odbc
Imports System.Xml.Xsl
Imports System.ComponentModel
Imports System.Threading
Imports System.IO.Ports
Imports FIAppStabilimento.MySql.Data
Imports System.Data.SqlClient
Namespace MySql.Data.MySqlClient
End Namespace

Answer 1

对于 mySQL 连接，不能使用 sqldataconnection。

首次下载 MySql 连接器/网络 然后添加以下引用： MySQL.Data

有时MySql for 以某种方式未在 .NET 选项卡下列出。转到"浏览"选项卡，然后导航到以下路径：

C：\Program Files (x86(\MySQL\MySQL Connector Net 6.6.4\Assemblies\v2.0 或 C：\Program Files (x86(\MySQL\MySQL Connector Net 6.6.4\Assemblies\v4.0 并添加 MySql.Data.dll 在公共类 Form1 之前添加以下代码 MYSQL.dll参考图像

Imports MySql.Data.MySqlClient

然后在公共类 Form1 下面添加以下声明

Dim conn As New MySqlConnection
Public Sub connect()
    Dim DatabaseName As String = "test"
    Dim server As String = "95.134.229.235"
    Dim userName As String = "web"
    Dim password As String = "fiautoppzione"
    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)
    Try
        conn.Open()
        MsgBox("Connected")
    Catch ex As Exception
        MsgBox(ex.Message)
    End Try
    conn.Close()
End Sub