如何在VB.net上从数据库到文本框获取数据 [英] How to get data from database to textbox on VB.net

问题描述

hi im new in Visual basic。我有一个按钮，当它点击，它会通过用户输入他们的ID找到学生，并将其输出到文本字段的数据。我不知道如果我做这个权利。因为我收到此错误[image] >> http://img812.imageshack.us /img812/7650/gq0z.png

btw这里是我的代码到目前为止。有人可以帮我吗？感谢！

  cmd.CommandText =Select * from Student where Student_id ='& id.Text& '
 cmd.Connection = db 
 
 dr = cmd.ExecuteReader 
 
尝试
 dr.Read（）
 id.Text = dr.GetValue（0）
 Lname.Text = dr.GetValue（1）
 Fname.Text = dr.GetValue（2）
 Mname.Text = dr.GetValue b $ b datet.Text = dr.GetValue（4）
 age.Text = dr.GetValue（5）
 male.Text = dr.GetValue（6）
 female.Text = dr .GetValue（7）
 status.Text = dr.GetValue（8）
 staddress.Text = dr.GetValue（9）
 cityAdd.Text = dr.GetValue（10）
 dr.Close（）
 
 Catch ex As Exception 
 MsgBox（+ ex.Message）
 dr.Close（）
结束Try 
  
 
 
解决方案
 
  cmd.CommandText =Select * from Student where Student_id ='& id.Text& 
  
更改为：
  if IsNumeric（id.text）Then 
 cmd.CommandText =Select * from student where Student_id = @ p1
 cmd.Prepare 
 cmd.Parameters .AddWithValue（@ p1，id.text）
 dr = cmd.ExecuteReader 
 .... 
否则
退出Sub 
结束如果
  
您可以这样做，或
  dr = cmd.ExecuteReader 
 
尝试
与dr 
 .Read（）
 id.Text = .GetValue（0）
 end with 
 dr.Close（）
  
或
 与dr 
 .read 
 id.text = .item（id）
 .close 
  
更容易阅读.... 
 
hi im new in Visual basic. I have a button that when its clicked, its gonna find the student via their ID inputted by the user and its gonna output the data to the textfields. I'm not pretty sure if im doing this right. because i'm getting this error [image] >> http://img812.imageshack.us/img812/7650/gq0z.png 

btw here's my code so far. can someone help me please? thanks!
        cmd.CommandText = "Select * from Student where Student_id = '" & id.Text & "'"
        cmd.Connection = db

        dr = cmd.ExecuteReader

        Try
            dr.Read()
            id.Text = dr.GetValue(0)
            Lname.Text = dr.GetValue(1)
            Fname.Text = dr.GetValue(2)
            Mname.Text = dr.GetValue(3)
            datet.Text = dr.GetValue(4)
            age.Text = dr.GetValue(5)
            male.Text = dr.GetValue(6)
            female.Text = dr.GetValue(7)
            status.Text = dr.GetValue(8)
            staddress.Text = dr.GetValue(9)
            cityAdd.Text = dr.GetValue(10)
            dr.Close()

        Catch ex As Exception
            MsgBox("" + ex.Message)
            dr.Close()
        End Try

解决方案
cmd.CommandText = "Select * from Student where Student_id = '" & id.Text & "'"
change to: 
if IsNumeric(id.text) Then
cmd.CommandText = "Select * from student where Student_id=@p1"
cmd.Prepare
cmd.Parameters.AddWithValue("@p1", id.text)
dr = cmd.ExecuteReader
....
Else
Exit Sub
End If
You can do it this way, or 
 dr = cmd.ExecuteReader

    Try
       with dr
        .Read()
        id.Text = .GetValue(0)
        end with
        dr.Close()
or 
with dr
    .read
    id.text = .item("id")
    .close
easier to read....

                        
这篇关于如何在VB.net上从数据库到文本框获取数据的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！