在插入数据库 ASP.NET VB.NET 之前将文本框字符串转换为整数

Question

我有一个网页，它在页面上显示了几个不同的网格视图和详细视图。我在网格视图中使用选择列来获取特定的单元格值并将其提供给 asp 标签。我正在尝试从标签中获取值并在我的 sql 查询中使用它，该查询将 'yes' 插入数据库中，基于将哪个值提供给标签，但是在执行查询时我不断收到错误的语法错误。

为了给您提供更多背景信息，我有两种类型的用户，学生和企业。网格视图显示来自学生用户的提交信息，然后商业用户可以选择这些信息作为获胜提交。我输入 asp 标签的列是提交 id 号 (PK)，它是数据库中的一个 int。根据提交 ID，业务用户可以选择通过单击启动我的 sql 命令以插入数据库的 asp 按钮将所选提交标记为获胜提交。我不确定使用什么转换方法来完成这项任务。

这是我的代码：

Imports System.Data

Partial Class InteriorBusinessProjectDetails
    Inherits System.Web.UI.Page
    Dim conn As New Data.SqlClient.SqlConnection("DatabaseConnetionString")

    Sub GridView1_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs)
        ' Get the currently selected row using the SelectedRow property.
        Dim row As GridViewRow = GridView1.SelectedRow

        lblSelectSubmission.Visible = True
        lblSubmission.Visible = True
        lblSubmissionID.Visible = True
        btnSelect.Visible = True
        btnCancel.Visible = True

        lblSubmissionID.Text = row.Cells(0).Text
    End Sub

    Protected Sub btnSelect_Click(sender As Object, e As EventArgs) Handles btnSelect.Click

        Dim SubmissionID As String = lblSubmissionID.Text
        Dim id As Integer = Convert.ToInt32(Convert.ToDecimal(SubmissionID))

        conn.Open()

        Dim cmd As New Data.SqlClient.SqlCommand(("INSERT INTO Submissions (Selected) VALUES ('Yes') WHERE SubmissionID=@SubmissionID"), conn)
        cmd.Parameters.Add("@SubmissionID", SqlDbType.Int).Value = id
        cmd.ExecuteNonQuery()

        conn.Close()

        lblSubmission.Visible = False
        lblSubmissionID.Visible = False
        btnSelect.Visible = False
        btnCancel.Visible = False
        lblSelectSubmission.Visible = True
        lblSelectSubmission.Text = "You have successfully chosen a submission for your project!"

    End Sub
End Class

这里抛出异常：

cmd.Parameters.Add("@SubmissionID", SqlDbType.Int).Value = id
cmd.ExecuteNonQuery()

这是堆栈跟踪：

StackTrace:
       at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
       at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
       at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)
       at System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady)
       at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString)
       at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async, Int32 timeout, Task& task, Boolean asyncWrite, SqlDataReader ds, Boolean describeParameterEncryptionRequest)
       at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, TaskCompletionSource`1 completion, Int32 timeout, Task& task, Boolean asyncWrite)
       at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(TaskCompletionSource`1 completion, String methodName, Boolean sendToPipe, Int32 timeout, Boolean asyncWrite)
       at System.Data.SqlClient.SqlCommand.ExecuteNonQuery()
       at InteriorBusinessProjectDetails.btnSelect_Click(Object sender, EventArgs e) in C:\Users\richard\Desktop\BRAINbait PLATINUM 11.24.15\InteriorBusinessProjectDetails.aspx.vb:line 32
       at System.Web.UI.WebControls.Button.OnClick(EventArgs e)
       at System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument)
       at System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument)
       at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument)
       at System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData)
       at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

前端的 GUI 带有我从中提取值的标签，以及启动我的 Click 事件的按钮：

<h2 style="margin-left:auto; margin-right:auto; text-align:center; color:#FF9933;"><asp:Label ID="lblSelectSubmission" runat="server" Text="Would you like to choose the following submission for your project?" Visible="false"></asp:Label></h2>
        <h2 style="margin-left:auto; margin-right:auto; text-align:center; color:#FF9933;"><asp:Label ID="lblSubmission" runat="server" Text="Submission Number: " Visible="false"></asp:Label><asp:Label ID="lblSubmissionID" runat="server" Text="" Visible="false"></asp:Label></h2>
        <center><asp:Button ID="btnSelect" runat="server" Text="Select" CssClass="submit" TabIndex="0" Visible="false" /><asp:Button ID="btnCancel" runat="server" Text="Cancel" CssClass="submit" TabIndex="1" Visible="false" /></center> 

Answer 1

您可以使用Val()

Val() - 将字符串中包含的数字作为适当类型的数值返回。

 Dim id As Integer = val(lblSubmissionID.Text)

和 imo，Dim SubmissionID As String = lblSubmissionID.Text 是不需要的

---

我怀疑真正的问题在于您的查询计划，即

insert into submissions(selected) ('Yes') WHERE submissionid=1 不是有效的插入语句，您需要在此处使用UPDATE

Protected Sub btnSelect_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btnSelect.Click
        Dim id As Integer = Val(lblSubmissionID.Text)
        conn.Open()
        Dim cmd As New Data.SqlClient.SqlCommand(("update Submissions  set Selected='Yes' WHERE SubmissionID=@SubmissionID"), conn)
        cmd.Parameters.Add("@SubmissionID", SqlDbType.Int).Value = id
        cmd.ExecuteNonQuery()
        conn.Close()
        lblSubmission.Visible = False
        lblSubmissionID.Visible = False
        btnSelect.Visible = False
        btnCancel.Visible = False
        lblSelectSubmission.Visible = True
        lblSelectSubmission.Text = "You have successfully chosen a submission for your project!"
    End Sub

Answer 2

Convert.ToInt16(idrow.Cells(0).Text) 将单元格转换为int

cmd.Parameters.Add("@SubmissionID", Convert.ToInt16(idrow.Cells(0).Text))

或

cmd.Parameters.Add("@SubmissionID", Id))

如果 Id 已经是整数