這是插入語句：sqlcmd.ExecuteReader("insert into t_login(id) values('" & CStr(Trim(TextBox1.Text)) & "'")
但是卻出錯不明白那里有問題

一樣提示
ID的類型是varchar(50)
'從字串 "insert into t_login (id) values " 至型別 'Integer' 的轉換是無效的。

Dim strcmd As String
        Dim sqlcn As SqlConnection = New SqlConnection(strcon)
        sqlcn.Open()
        strcmd = "select id from t_login"
        Dim sqlcmd As SqlCommand = New SqlCommand(strcmd, sqlcn)
        Dim dr As SqlDataReader
        dr = sqlcmd.ExecuteReader
        Do While dr.Read
            If Trim(TextBox1.Text) = dr.Item(0) Then
                MsgBox("該用戶名已存在!")
                Exit Sub
            Else
                Dim sqlcmdcommandtext As String
                sqlcn.Close()
                sqlcn.Open()
                sqlcmdcommandtext = "insert into t_login (id) values ('" & CStr(Trim(TextBox1.Text)) & "'）"
                sqlcmd.ExecuteNonQuery()

                MsgBox("申請成功，請登入!")
                Exit Sub
            End If
        Loop


謝謝你了，這是我做的，你幫忙看下有什么問題

是的並且是剛轉

謝謝可以了

Try
Catch ex As Exception
End Try
這是什么語法

也就是說當錯誤時就運行，而end try 是結束try過程的

Try
            If mydataset.Tables("t_login").Rows(0).Item(1) = Trim(TextBox2.Text) Then
                userinf(0) = Trim(TextBox1.Text)
                userinf(1) = Trim(TextBox2.Text)
            Else
                MsgBox("密码错误")
                TextBox2.Text = ""
                Exit Sub
            End If

        Catch ex As Exception
            MsgBox("用户不存在")
            TextBox1.Text = ""
            TextBox2.Text = ""
            Label3.Text = ""
        End Try
那麼祂這里什么意思啊，祂里面代碼完全沒問題啊

謝謝啦，我已經理解了
請問這個是什么意思這個在書上無解釋
try
if a<>a then a=b
Catch ex As Exception
if a=a then a=a
Finally
SqlConnection1.Close()
end try