VB.NET & SQL：ConnectionString 属性尚未初始化

Question

我试图创建一个搜索，其中SQL查询取决于一个单选按钮和一个文本框。表格、文本框和单选按钮都在同一个表单上。我正在使用Microsoft Visual Studio 2012 for Web，并试图更改表单上GridView对象的数据源。然而，我一直得到错误:

ConnectionString属性未初始化

我该如何解决这个问题?下面是我的完整代码:

Protected Sub btnSearch_Click(sender As Object, e As ImageClickEventArgs) Handles btnSearch.Click
    Dim sqlQuery As String = ""
    If radClient.Checked = True Then
        GridView1.Visible = False
        sqlQuery = "SELECT * FROM Sales WHERE ClientID = '" & txtSearch.Text & "'"
    ElseIf radItem.Checked = True Then
        GridView1.Visible = False
        sqlQuery = "SELECT * FROM Sales WHERE ItemID = '" & txtSearch.Text & "'"
    ElseIf radUser.Checked = True Then
        GridView1.Visible = False
        sqlQuery = "SELECT * FROM Sales WHERE UserID = '" & txtSearch.Text & "'"
    ElseIf radUser.Checked = False And radClient.Checked = False And radItem.Checked = False Then
        ErrorLabel.Text = "Error: You have not chosen a search criteria."
        Return
    End If
    SqlDataSource3.SelectCommand = sqlQuery
    SqlDataSource3.DataBind()
End Sub

感谢@Steve， @MuhammadOmar， @Westie和@AmitApollo在我之前的线程中的代码帮助。

谢谢!

Answer 1

你应该这样做

创建一个全局连接变量

dim con as new SQLConnection
con.connectionsting = "Set your connection string"
con.open

当你写你的代码之后，然后写

con.close

它会解决你的问题