SQL选择参数 [英] SQL Select parameter

问题描述

我是vb.net的新手。我的错误输入字符串格式不正确。我已经使用不同的代码在sql select查询中添加参数。



我想问一下在VB.net中添加参数的最佳方法是什么查询？



提前致谢。

Hi I''m new to vb.net.I''m having error input string is not in the correct format. I already used different codes for adding a parameter in sql select query.

I would like to ask what is the best way of adding a parameter in a VB.net select query?

Thanks in advance.

Dim strsql As String = "Select * from [users] where [userid]=@uid and [password]=@pword"


SQLCOn = New SqlConnection(Constring)

        Try
            SQLCOn.Open()
            Dim cmd As New SqlCommand(strsql, SQLCOn)

            1 cmd.Parameters.AddWithValue("@uid", UsernameTextBox.Text)
              cmd.Parameters.AddWithValue("@pword", PasswordTextBox.Text)


            2 cmd.Parameters.Add(New SqlParameter("@uid", UsernameTextBox.Text))
              cmd.Parameters.Add(New SqlParameter("@pword", PasswordTextBox.Text))

            3 cmd.Parameters.Add("@uid", SqlDbType.VarChar).Value = UsernameTextBox.Text
              cmd.Parameters.Add("@pword", SqlDbType.VarChar).Value = PasswordTextBox.Text


            4 cmd.Parameters("@uid").Value = UsernameTextBox.Text
              cmd.Parameters("@pword").Value = PasswordTextBox.Text

            'count = Convert.ToInt32(cmd.ExecuteScalar())

            If Convert.ToInt32(cmd.ExecuteScalar()) >= 1 Then
                MsgBox("Login success", vbInformation)
                Me.Hide()
            Else
                MsgBox("Invalid login", vbExclamation)
            End If

        Catch ex As Exception
            MsgBox(ex.ToString, vbExclamation)
        End Try

推荐答案

我的错误。我应该用过。

My mistake. I should have used.

"Select count(*) from [users] where [userid]=@uid and [password]=@pword"

自从我使用

since I used

Convert.ToInt32(cmd.ExecuteScalar())>= 1

这需要数字结果。



1,2和3在我的选择查询中修复错误后工作。

which requires numeric result.

1, 2 and 3 worked after I fixed my error in my select query.

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