无法从 SQL Server 数据库中读取数据

Question

我从 SQL Server 数据库读取数据时遇到问题。主要是我想从数据库中读取数据并在标签控件中显示数据。但令人担忧的是它无法读取数据。我将向您展示代码 sn-p 并且很乐意考虑任何 cmets/建议。

Option Explicit On

Imports System.Data
Imports System.Data.OleDb

Partial Class ViewDetail
    Inherits System.Web.UI.Page
    Dim con As OleDbConnection
    Dim cmd As OleDbCommand
    Dim dr As OleDbDataReader
    Dim InstructorID As Integer

Protected Sub Page_Load(sender As Object, e As EventArgs) Handles Me.Load
    InstructorID = Request.QueryString("Instructor_ID")
    Integer.TryParse(lblID.Text, InstructorID)
    con = New OleDbConnection("Provider=SQLNCLI11;Data Source=ARIES-PC\SQLEXPRESS;Integrated Security=SSPI;Initial Catalog=SchoolDB")
    con.Open()
    cmd = New OleDbCommand("SelectData", con)
    cmd.CommandType = CommandType.StoredProcedure
    cmd.Parameters.AddWithValue("@id", InstructorID)
    dr = cmd.ExecuteReader
    If dr.HasRows Then
        While dr.Read
            lblID.Text = dr("Instructor_ID").ToString
            lblFirstname.Text = dr("FirstName").ToString
            lblLastname.Text = dr("LastName").ToString
            lblAddress.Text = dr("Address").ToString
            lblContact.Text = dr("Contact_Number").ToString
        End While
    End If
    dr.Close()
    cmd.Dispose()
    con.Close()
End Sub
End Class

Answer 1

这一行似乎完全错误

Integer.TryParse(lblID.Text, InstructorID)

此行在 Page_Load 事件中获取 lblID.Text 中的当前值，并尝试设置 InstructorID 的值。但是您的代码似乎想要来自 QueryString 传递的包含实际值的这个值。

如果您确定 QueryString 包含有效整数，则删除该行并添加

InstructorID = Convert.ToInt32(Request.QueryString("Instructor_ID"))