写两个函数，一个检测是否有重复用户，第二个插入
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检测属用户是否存在
private function checkUser(byval uname as string) as boolean
dim sql as string = "select * from [user] where username=" uname
dim cmd as sqlcommand = new sqlcommand(sql,conn)
dim read as sqldatareader = cmd.excutereader
dim result as boolean = read.hasrows
cmd=nothing
return result
end function
新增用户
private sub adduser(byval uname as string,byval password as string)
if checkUser(uname)
messagebox.show("用户已存在")
exit sub
end if
try
dim sql as string = "insert into [user](username,password) values(@uname,@upass)"
dim cmd as sqlcommand = new sqlcommand(sql,conn)
cmd.parameters.add("@uname",sqldbtype.varchar).value=uname
cmd.parameters.add("@upass",sqldbtype.varchar).value=password
cmd.ExecuteNonQuery
cmd=nothing
messagebox.show("用户添加成功！")
catch ex As Exception
messagebox.show("用户添加失败！" + ex.message)
end try
end sub
改为：
sql = "insert into 表1 values(用户名='" TextBox1.Text "' ,密码='" TextBox2.Text "')"
Private Sub Button _Click（ByVal sender As System Object ByVal e As System EventArgs） Handles Button Click
If TextBox Text = Or TextBox Text = Then
Label Text = 请确认您的输入！
Return
End If
Dim sql As String = select * from pwd where stu_id=@stu_id and pwd=@pwd
Dim m As SqlCommand = New SqlCommand（sql conn）
m Parameters Add（New SqlParameter（ @stu_id SqlDbType Int ））
m Parameters（ @stu_id ） Value = TextBox Text
m Parameters Add（New SqlParameter（ @pwd SqlDbType Char ））
m Parameters（ @pwd ） Value = TextBox Text
Dim dr As SqlDataReader
conn Open（）
dr = m ExecuteReader
If dr Read Then
Session（ stu_id ） = TextBox Text
dr Close（）
m Cancel（）
Dim sql_ As String = update stu_base set point=point+ where stu_id=@stu_id
m = New SqlCommand（sql_ conn）
m Parameters Add（New SqlParameter（ @stu_id SqlDbType Int ））
m Parameters（ @stu_id ） Value = Session（ stu_id ）
m ExecuteNonQuery（）
m Cancel（）
Response Redirect（ detail aspx？stu_id= Session（ stu_id ） ）
Else
Label Text = 您还没有注册或账号密码错误
End If
End Sub
Private Sub Button _Click（ByVal sender As System Object ByVal e As System EventArgs） Handles Button Click
TextBox Text =
TextBox Text =
lishixinzhi/Article/program/net/201311/13960
创建完相应的用户名，密码控件之后，输入以下代码：
Imports System.Data.OleDb
Public Class Form1
Private Sub cmdok_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdok.Click
Dim m_username As String
Dim m_userpwd As String
Dim cmd_result As MsgBoxResult
Dim m_da As New OleDbDataAdapter
Dim m_ds As New DataSet
Dim m_command As New OleDbCommand
Dim strsql As String
m_username = txtusername.Text
m_userpwd = txtuserpwd.Text
strsql = " select * from user_info where username='" m_username "' and userpwd='" m_userpwd "'"
OleDbConnection1.Open()
m_command.CommandType = CommandType.Text
m_command.CommandText = strsql
m_command.Connection = OleDbConnection1
m_da.SelectCommand = m_command
m_da.Fill(m_ds, "user_info")
If m_ds.Tables("user_info").Rows.Count 0 Then
cmd_result = MsgBox("欢迎登录", MsgBoxStyle.OKOnly, "提示")
Else
MsgBox("登录失败，请确认用户名和密码")
End If
End Sub
End Class