Question

我的sql-query的结果是一个单一的值，我希望显示在一个标签但不知道如何。我有一个创建数据集的解决方案，将查询结果放入该数据集，并按行（0），列（0）获取，但我想有更聪明的方法。

Private myquery As String

Sub New(ByVal query As String)
    myquery = query
End Sub
Public Sub query_Send()
    Dim myconn As New SqlConnection("Data Source=DB;Integrated Security=TRUE")
    Dim mycmd As SqlCommand = New SqlCommand(Me.myQuery, myconn)
    Dim myTable As New DataTable
    Dim previousConnectionState As ConnectionState = myconn.State
    Try
        If myconn.State = ConnectionState.Closed Then
            myconn.Open()
            Dim myDA As New SqlDataAdapter(mycmd)
            myDA.Fill(myTable)
            tb.text = **...**
        End If
        If previousConnectionState = ConnectionState.Closed Then
            myconn.Close()
        End If
    End Try
End Sub

Answer 1

您可以使用SqlCommand.ExecuteScalar Method

Dim querystr as String = "select value from MyTable where ID=5"
Dim mycmd As New SqlCommand(querystr, connection)
dim value as Object = mycmd.ExecuteScalar()

您可以将value放入文本框。 ExecuteScalar返回结果集第一行的第一个值（相当于row(0).column(0)）当没有返回记录时，value为nothing。

Answer 2

尝试更多内容：

    Using myconn As New SqlConnection("Data Source=DB;Integrated Security=TRUE")
        Dim myDA As New SqlDataAdapter()
        myDA.SelectCommand = New SqlCommand(myQuery, myconn)
        myDA.Fill(myTable)
        Return myTable 
    End Using

或者你可以通过

获得第一行中的第一项

myTable.Rows(0).ItemArray(0).ToString()

从sql-query获取单个值到文本框中

2 个答案: