Question

如何编写一个从数据库中获取信息的sql查询，然后将其放入标签中的文本中？我不确定该怎么做。

Answer 1

MSDN有很多通过ADO.NET获取数据的例子。例如。 http://msdn.microsoft.com/library/dw70f090

您需要调整连接和命令类型（以及连接字符串）以使其适用于My SQL。如果您有My SQL的ODBC驱动程序，那么只需更改连接字符串即可遵循ODBC示例。

Answer 2

对于在.NET中使用MySQL，我建议你this tutorial，特别是你的问题第6部分，关于用MySQLDataReader读取数据。

一个（几乎正常工作）的样本，通过复制和粘贴从那里进行一些更改：

Private Sub getData()
      Dim conn As New MySqlConnection
      Dim myCommand As New MySqlCommand
      Dim myReader As MySqlDataReader
      Dim SQL As String

      SQL = "SELECT LabelContent FROM myTable"

      conn.ConnectionString = myConnString ' your connection string here'

      Try
           conn.Open()

           Try
                myCommand.Connection = conn
                myCommand.CommandText = SQL

                myReader = myCommand.ExecuteReader

                                        ' loop through all records'
                While myReader.Read
                 Dim myLabelValue as String
                 myLabelValue = myReader.GetString(myReader.GetOrdinal("LabelContent"))

                 ' ... do something with the value, e.g. assign to label '
                End While
           Catch myerror As MySqlException
                MsgBox("There was an error reading from the database: " & myerror.Message)
           End Try
      Catch myerror As MySqlException
            MessageBox.Show("Error connecting to the database: " & myerror.Message)
      Finally
            If conn.State <> ConnectionState.Closed Then conn.Close()
      End Try
End Sub

Answer 3

要从ms access 2007数据库中选择一个要标记的列，请执行以下步骤

创建ms访问数据库，例如我将名称设为“test.accdb”，并使1列（例如列名称为“ColumnName”）和一个名为“Table1”的表
将其保存在任何文件夹
打开vb 2008并制作一张表格
首次撰写时导入adodb
在类

Sub lihat()
    Dim str As String = "select * from Table1"
    Dim cn As New OleDb.OleDbConnection
    Dim com As New OleDb.OleDbCommand
    Dim adp As OleDb.OleDbDataReader
    With cn
        .ConnectionString = "Provider=Microsoft.ace.oledb.12.0;data source=test.accdb;persist security info=false"
        .Open()
    End With

    With com
        .Connection = cn
        .CommandText = str
    End With

    adp = com.ExecuteReader
    adp.Read()


    Label1.Text = adp(1)
    cn.Close()
End Sub

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    lihat()
End Sub

adp（1）上的数字1是Table1上的列数。

SQL和VISUAL BASIC 2008查询

3 个答案: