Question

我在表中有一个包含消息的列，我希望此消息显示在标签中。这是我的代码，目前没有填充标签。

Protected conString As String = ConfigurationManager.AppSettings("sqldirectory")
Dim cnn As New SqlConnection(conString)
    Dim cmd As New SqlCommand("select message from [database].[dbo].[table]")
    Dim dr As SqlDataReader

    Try
        cnn.Open()
        dr = cmd.ExecuteReader()
        lblMsg.Text = dr(0).ToString
    Catch ex As Exception
        dr = Nothing
    Finally
        cnn.Close()
    End Try

Answer 1

好的，在玩完之后，我想出了这个有效的方法

Protected conString As String = ConfigurationManager.AppSettings("sqldirectory")
Dim cnn As New SqlConnection(conString)
Dim cmd As New SqlCommand("select message from [database].[dbo].[table]", cnn)
Dim dr As SqlDataReader
Dim msg As String
Try
    cnn.Open()
    dr = cmd.ExecuteReader(System.Data.CommandBehavior.CloseConnection)
    While dr.Read()
        msg = dr("message")
        lblMsg.Text = msg
    End While
Catch ex As Exception
    dr = Nothing
Finally
    cnn.Close()
End Try

Answer 2

我在寻找别的东西时意外地遇到了这个。有一种更简单的方法可以做到这一点。

我很想创建一些常见的app_code来执行此操作。使用以下代码在项目和common.vb文件中创建app_code文件夹：

Imports Microsoft.VisualBasic
Imports System.Data.SqlClient
Imports System.Data

Namespace GetDBResult
Public Class DB
    Public Shared Function GetRecord(sql As String) As String
        Dim result As String
        Dim connection As New SqlConnection(ConfigurationManager.ConnectionStrings("YourConnectionString").ToString)
        connection.Open()

        Dim command As New SqlCommand(sql, connection)

        Try
            If command.ExecuteScalar IsNot System.DBNull.Value Then
                result = command.ExecuteScalar
            Else
                result = ""
            End If
        Catch ex As Exception
            Throw ex

        Finally
            connection.Close()
        End Try

        Return result
    End Function
    End Class
    End Namespace

从那里，您可以从任何vb代码调用该函数，从而可以非常轻松地从数据库中获取字段以将其分配给标签。如下：

    Dim sql as string = "your sql query which should return one row and column"
    label1.text = DB.GetRecord(sql)

节省了大量的重新输入。

哦，请记住在您希望使用app_code的任何视频中导入您的代码

    Imports GetDBResult

非常感谢，尼尔

从sql server中的单个字段填充标签

2 个答案: