从插入中获取会话 - C# 和 MySQL

Question

我以前从未这样做过，所以我希望你们中的一些人知道如何去做。

基本上我在 CreateModule 页面上进行了插入，然后我想获取新的 ModuleID（它是在数据库中创建的，我没有插入）和 ModuleTitle 并将其带到 CreateModule2 页面。

我非常感谢所有的帮助。

C#

protected void CreateNewModule_Click(object sender, EventArgs e)
        {
            // open new connection
            SqlConnection connect1 = new SqlConnection(ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString);
            connect1.Open();

            // initalise variables for update
            String Title = ModuleTitleText.Text;
            String Mtext = ModuleTextText.Text;
            String Com = CompulsoryDropdown.Text;
            String CAT = CATpointsText.Text;
            String Lev = LevelText.Text;
            String Ass = AssessmentText.Text;
            String MCode = ModuleCodeText.Text;
            String Status = ModuleStatusDropdown.Text;

            // convert string to Int
            Int32 Levconverted = Convert.ToInt32(Lev);
            Int32 CATconverted = Convert.ToInt32(CAT);
            

            // Insert Query to Add new student record to student records table in database
            String queryInsert = "INSERT INTO Module_Info (ModuleTitle, ModuleText, Compulsory, CATpoints, Level, Assessment, ModuleCode, ModuleStatus) VALUES ('" + Title + "', '" + Mtext + "', '" + Com + "', '" + CAT + "', '" + Lev + "', '" + Ass + "',  '" + MCode + "', '" + Status + "'); SELECT  LAST_INSERT_ID()";

            // excute insert query
            SqlCommand myCommand = new SqlCommand(queryInsert, connect1);
            myCommand.Parameters.Add("@title", SqlDbType.NVarChar).Value = Title;
            int idmodule = Convert.ToInt32(myCommand.ExecuteScalar());
            
            

            // alerts for successfull upload
            Response.Write("<script type='text/javascript'>");
            Response.Write("alert('New Module has been added. Please select a course to align the module to in the next page.');");
            Response.Write("document.location.href='CreateModule2.aspx';");
            Response.Write("</script>");
        }

然后这是前端代码。

<table style="width: 100%;">
                <tr>
                    <td><asp:Label ID="ModuleTitle" runat="server" Text="Module Title" Font-Bold="true"></asp:Label></td>
                    <td><asp:TextBox ID="ModuleTitleText" runat="server" TextMode="MultiLine" style="overflow:hidden" onkeyup="AutoExpand(this)" Rows="1" width="700px" ></asp:TextBox>
                        <asp:RequiredFieldValidator runat="server" id="reqModuleTitle" controltovalidate="ModuleTitleText" 
                            errormessage="* Please enter the module title" ForeColor="Red" Font-Bold="true" Font-Size="Small" /></td>
                </tr>
                <tr>
                    <td><asp:Label ID="ModuleText" runat="server" Text="Module Text" Font-Bold="true" ></asp:Label></td>
                    <td><asp:TextBox ID="ModuleTextText" runat="server" TextMode="MultiLine" style="overflow:hidden" onkeyup="AutoExpand(this)" Rows="4" width="800px"></asp:TextBox>
                        <asp:RequiredFieldValidator runat="server" id="reqModuleText" controltovalidate="ModuleTextText" 
                            errormessage="*Please enter the Module Information" ForeColor="Red" Font-Bold="true" Font-Size="Small" /></td>
                </tr>
                <tr>
               <!-- dropdown list to select value-->
                  <td><asp:Label ID="Compulsory" runat="server" Text="Compulsory Status" Font-Bold="true" ></asp:Label> </td>
                    <td><asp:DropDownList ID="CompulsoryDropdown" runat="server">
                        <asp:ListItem Value="true">Compulsory</asp:ListItem>
                        <asp:ListItem Value="false">Non-Compulsory</asp:ListItem>
                </asp:DropDownList></td>
                </tr>
                <tr>
                    <td><asp:Label ID="CATpoints" runat="server" Text="CATpoints" Font-Bold="true"></asp:Label></td>
                    <td><asp:TextBox ID="CATpointsText" runat="server" TextMode="MultiLine" style="overflow:hidden" onkeyup="AutoExpand(this)" Rows="1" width="100px"></asp:TextBox>
                        <asp:RequiredFieldValidator runat="server" id="reqCATpoints" controltovalidate="CATpointsText" 
                            errormessage="*Please enter the A-Level Requirements" ForeColor="Red" Font-Bold="true" Font-Size="Small" /></td>
                </tr>
                <tr>
                    <td><asp:Label ID="Level" runat="server" Text="Level" Font-Bold="true"></asp:Label></td>
                    <td><asp:TextBox ID="LevelText" runat="server" TextMode="MultiLine" style="overflow:hidden" onkeyup="AutoExpand(this)" Rows="1" width="100px"></asp:TextBox>
                        <asp:RequiredFieldValidator runat="server" id="reqLevel" controltovalidate="LevelText" 
                            errormessage="*Please enter the Level of the module" ForeColor="Red" Font-Bold="true" Font-Size="Small" /></td>
                </tr>
                <tr>
                    <td><asp:Label ID="Assessment" runat="server" Text="Assessment" Font-Bold="true"></asp:Label></td>
                    <td><asp:TextBox ID="AssessmentText" runat="server" TextMode="MultiLine" style="overflow:hidden" onkeyup="AutoExpand(this)" Rows="1" width="600px"></asp:TextBox>
                        <asp:RequiredFieldValidator runat="server" id="ReqAssessment" controltovalidate="AssessmentText" 
                            errormessage="*Please enter the Assessment details" ForeColor="Red" Font-Bold="true" Font-Size="Small" /></td>
                </tr>
                <tr>
                    <td><asp:Label ID="ModuleCode" runat="server" Text="Module Code" Font-Bold="true" ></asp:Label>  </td>
                    <td><asp:TextBox ID="ModuleCodeText" runat="server"  TextMode="MultiLine" style="overflow:hidden" onkeyup="AutoExpand(this)" Rows="1" width="300px"></asp:TextBox>
                        <asp:RequiredFieldValidator runat="server" id="ReqModuleCode" controltovalidate="ModuleCodeText" 
                            errormessage="*Please enter the module code" ForeColor="Red" Font-Bold="true" Font-Size="Small" />
                    </td>
                </tr>
                <tr>
               <!-- dropdown list to select value-->
                  <td><asp:Label ID="ModuleStatus" runat="server" Text="Module Status" Font-Bold="true" ></asp:Label> </td>
                    <td><asp:DropDownList ID="ModuleStatusDropdown" runat="server">
                        <asp:ListItem Value="Running">Running</asp:ListItem>
                        <asp:ListItem Value="Suspended">Suspended</asp:ListItem>
                        <asp:ListItem Value="Withdrawn">Withdrawn</asp:ListItem>
                </asp:DropDownList></td>
            </tr>
               <tr>
                    <td>&nbsp;</td>
                    <td>&nbsp;</td>
               </tr>
               <tr>
                    <td><asp:Button ID="SubmitModule" runat="server" Text="Submit" OnClick="CreateNewModule_Click" /></td>
               </tr>
            </table>

Answer 1

您需要将此附加到 SQL 字符串的末尾：

SELECT SCOPE_IDENTITY()

这将返回新创建记录的 ID。然后，您可以通过将 myCommand.ExecuteQuery() 替换为：

int id = myCommand.ExecuteScalar();

然后，您可以使用带有 id 的 Response.Redirect 进入下一页，并使用它从新创建的记录中加载任何内容。

Answer 2

您的代码很丑陋、有缺陷，并且要求进行 SQL 注入。只是祈祷没有人输入像'DROP TABLE'Module_Info'这样的文本；在 ModuleTitleText.. 也就是说，将您的查询更改为：

String queryInsert = "INSERT INTO Module_Info (ModuleTitle, ModuleText, Compulsory, CATpoints, Level, Assessment, ModuleCode, ModuleStatus) VALUES ('" + Title + "', '" + Mtext + "', '" + Com + "', '" + CAT + "', '" + Lev + "', '" + Ass + "',  '" + MCode + "', '" + Status + "'); SELECT  LAST_INSERT_ID()"

然后使用：

int result = (int) myCommand.ExecuteScalar();

假设你的 id col 设置为 AUTO_INCREMENT

编辑。 在 SQL Server 中将其更改为 SCOPE_IDENTITY()

Answer 3

首先您应该知道字符串连接在数据库代码中是一种非常糟糕的做法。它会导致Sql Injections 和解析问题。对于所有这些原因，更好的做法是使用参数化查询，然后取回表中最后插入的标识，修复非常简单

String queryInsert = @"INSERT INTO Module_Info 
        (ModuleTitle, ModuleText, Compulsory, CATpoints, Level, 
         Assessment, ModuleCode, ModuleStatus) VALUES 
        (@title, @mtext, @Com, @cat, @lev, @Ass, @MCode, @Status);
        SELECT SCOPE_IDENTITY()";

SqlCommand myCommand = new SqlCommand(queryInsert, connect1);
myCommand.Parameters.Add("@title", SqlDbType.NVarChar).Value = Title;
.... ...
// and so on with all other parameters required
// paying attention to use the appropriate SqlDbType for the 
// field updated by the parameter value...

// Don't run ExecuteNonQuery, but ExecuteScalar to get the last
// value returned by SCOPE_IDENTITY()
int idmodule = Convert.ToInt32(myCommand.ExecuteScalar());

如您所见，查询包含两条指令，最后一条返回插入到 module_info 表中的 ID，您可以使用 ExecuteScalar 获取它

等待有关 MySql 与 Sql Server 问题的澄清。我将向您展示相同的代码，但用于 MySql

String queryInsert = @"INSERT INTO Module_Info 
        (ModuleTitle, ModuleText, Compulsory, CATpoints, Level, 
         Assessment, ModuleCode, ModuleStatus) VALUES 
        (@title, @mtext, @Com, @cat, @lev, @Ass, @MCode, @Status);
        SELECT last_insert_id()";

MySqlCommand myCommand = new MySqlCommand(queryInsert, connect1);
myCommand.Parameters.Add("@title", MySqlDbType.VarChar).Value = Title;

注意 last_insert_id 函数的使用，以及 MySql 的类而不是 Sql Server 的使用

关于将其传递给您的调用页面。通常的方法是将结果放入查询字符串中，然后在调用的页面中查看 QueryString 集合来获取它

    Response.Write("<script type='text/javascript'>");
    Response.Write("alert('New Module has been added. Please select a course to align the module to in the next page.');");
    Response.Write("document.location.href='CreateModule2.aspx?ModuleID=" + idmodule + "&Title=" + Title + "';");
    Response.Write("</script>");