记录插入错误的表。任何想法为什么以及如何解决它？

Question

这对我来说很奇怪。

我尝试获取此代码的存储过程版本，但没有成功。

这是一款培训应用。用户必须先注册才能创建帐户。

然后他们使用自己的帐户注册课程。

首先，代码会检查该用户是否已经注册了特定课程。

如果没有，则注册用户。如果是，请通知该用户他/她已经注册。

这个位有效。

如果用户尚未注册并正在尝试注册，请检查是否仍有可用席位。如果是，请注册用户。如果没有更多座位可用，则通过将用户插入一个名为 tblWaitinglist 的表中，将用户列入等候名单。

到目前为止，每次我尝试插入新记录时，它都会说，班级已满，用户正在等待列表中。

这不是真的。类完全是空的。

共有 45 个座位​​。

到目前为止，所有座位都已空位。

我到底做错了什么？

它甚至没有插入等候名单。它只是给出了它所做的信息。

请在下面查看我的代码，并提前非常感谢。

Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs)
    Dim username = Session("Username")
    Dim connStr As String = ConfigurationManager.ConnectionStrings("DBConnectionString").ConnectionString
    Dim conn As New SqlConnection(connStr)
    conn.Open()
    Try

        Dim s As String
        Dim counter As Integer

        'If user already registered for a class, alert user
        s = "SELECT Count(*) FROM tblTrainings WHERE Username = '" & username & "' AND CourseID = " & Request.QueryString("cosId") & "  AND LocationID = " & Request.QueryString("locid") & " AND dateId = " & Request.QueryString("iddate") & ""
        'Response.Write(s)
        'Response.End()
        Dim connSt As String = ConfigurationManager.ConnectionStrings("DBConnectionString").ConnectionString
        Dim connc As New SqlConnection(connSt)
        Dim cmdc As New SqlCommand(s, connc)
        connc.Open()
        cmdc.ExecuteNonQuery()
        counter = cmdc.ExecuteScalar()


        '   Now let's see if we found existing record of registration
        If counter = 0 Then 'User has not registered for this training. In that case, check to see there are still seats available.
            Dim SeatsAvailable As Integer
            SeatsAvailable = 0

            s = " SELECT SeatsAvailable = (Select Seating_Capacity  - (Select count(*) from tblTrainings where courseId = @cosId) from tblLocations WHERE LocationId = @Locid)"
            'Response.Write(s)
            'Response.End()
            Dim cmdB As New SqlCommand(s, conn)
            cmdB.Parameters.AddWithValue("@cosID", Request.QueryString("cosId"))
            cmdB.Parameters.AddWithValue("@locID", Request.QueryString("locid"))
            cmdB.ExecuteNonQuery()


            If SeatsAvailable > 0 Then 'Ok there are still seats available. Sign this user up.
                s = "INSERT INTO tblTrainings (CourseId, LocationId, dateId,username) VALUES (@CosID, @LocID, @dat, @Username)"
                Dim cmd = New SqlCommand(s, conn)
                cmd.Parameters.AddWithValue("@cosID", Request.QueryString("cosId"))
                cmd.Parameters.AddWithValue("@locID", Request.QueryString("locid"))
                cmd.Parameters.AddWithValue("@dat", Request.QueryString("iddate"))
                cmd.Parameters.AddWithValue("@UserName", username)
                'Response.Write(s)
                'Response.End()
                cmd.ExecuteNonQuery()
                Dim cmdGetKey As New SqlCommand("SELECT @@IDENTITY", conn)
                Dim skey As Integer = cmdGetKey.ExecuteScalar()
                Session("TrainingId") = skey
                conn.Close()
                confirmRegistraction()
                Label1.ForeColor = System.Drawing.Color.Red
                Label1.Text = "Congratulations! You have been registered for this class. Please check your email inbox for details"
            Else 'No seats remain. So, put user on waiting list
                s += "INSERT INTO tblWaitingList (CourseId, LocationId, dateId,username) VALUES (@CosID, @LocID, @dat, @Username)"
                Dim cmd = New SqlCommand(s, conn)
                cmd.Parameters.AddWithValue("@cosID", Request.QueryString("cosId"))
                cmd.Parameters.AddWithValue("@locID", Request.QueryString("locid"))
                cmd.Parameters.AddWithValue("@dat", Request.QueryString("iddate"))
                cmd.Parameters.AddWithValue("@UserName", username)
                'Response.Write(s)
                'Response.End()
                cmd.ExecuteNonQuery()
                Dim cmdGetKey As New SqlCommand("SELECT @@IDENTITY", conn)
                Dim skey As Integer = cmdGetKey.ExecuteScalar()
                Session("TrainingId") = skey
                conn.Close()
                onWaitingList()
                'Display some feedback to the user to let them know it was processed
                Label1.ForeColor = System.Drawing.Color.Red
                Label1.Text = "Sorry, but this class is full. However, you have been placed on waiting list."
            End If

        Else
            'Alert user that s/he has already registered for this class
            Label1.ForeColor = System.Drawing.Color.Red
            Label1.Text = "You have already signed up for this training."
        End If

    Catch

        'If the message failed at some point, let the user know
        Label1.ForeColor = System.Drawing.Color.Red
        Label1.Text = "Your record failed to save, please try again."

    End Try
End Sub

Answer 1

看起来您从未将 SeatsAvailable 设置为零以外的任何值。您的 s 变量可能就是您想要查看的内容。

INSERT 失败完全是另一个问题。