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ASP.NET获取自增长列（标识列）的ID

作者：互联网

原文链接：http://www.cnblogs.com/kangshifu/archive/2008/11/22/1338860.html

来源：http://www.study-code.com/dotnet/aspnet/67500.htm

 

问题
疑惑：如何获取自增长列（标识列）的ID，并写入另一张表。

关系图


实现要点
1， 如何获取新插入记录生成的 ID：Sql Server 和 Access（当使用 Jet ADO，当然包括ADO.NET，连接时）均支持 @@Identity 全局变量，返回在当前会话的所有表中生成的最后一个标识值
2，同时写入多张表需要显示使用事务

MS Access 版本

<%@ Page Language="C#" %>
<%@ Import Namespace="System.Data" %>
<%@ Import Namespace="System.Data.OleDb" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">

    string connStr;

    protected void Page_Load(object sender, EventArgs e)
    {
        connStr = "provider=Microsoft.Jet.OleDb.4.0;data source=" + Server.MapPath("~/App_Data/DemoManyToMany.mdb");
    }
   
    protected void btnLogin_Click(object sender, EventArgs e)
    {
        if (chkRoles.SelectedIndex == -1) throw new Exception("至少选择一个角色。");       
       
        string sqlInserUser = "INSERT INTO [User]([UserName], [Password]) VALUES(?, ?)";
        string sqlInserUserRoel = "INSERT INTO UserRole([UserId], [RoleId]) VALUES(?, ?)";
        string sqlSelectNewUserId = "SELECT @@Identity"; // OR "SELECT MAX([UserId]) FROM [User]";
        using (OleDbConnection conn = new OleDbConnection(connStr)) {           
            conn.Open();
            // 显示开启事务
            OleDbTransaction trans = conn.BeginTransaction();           
            OleDbCommand cmd = conn.CreateCommand();
            // 关联事务
            cmd.Transaction = trans;          
           
            try {
                cmd.CommandText = sqlInserUser;
                cmd.Parameters.Add("UserName", txtUserName.Text);
                cmd.Parameters.Add("Password", txtPassword.Text);
                // 插入 User
                cmd.ExecuteNonQuery();                              

                cmd.CommandText = sqlSelectNewUserId;
                // 读取新插入 UserId
                int newUserId = (int)cmd.ExecuteScalar();

                // 仅供测试
                if (chkGeneratError.Checked) throw new Exception("创建用户时发生错误。");

                cmd.CommandText = sqlInserUserRoel;
                cmd.Parameters.Clear();
                cmd.Parameters.Add("UserId", OleDbType.Integer);
                cmd.Parameters.Add("RoleId", OleDbType.Integer);
                cmd.Parameters[0].Value = newUserId;
                // 遍历可选角色列表
                foreach (ListItem item in chkRoles.Items) {
                    if (item.Selected) {
                        cmd.Parameters[1].Value = item.Value;
                        // 写入中间关系表 UserRole
                        cmd.ExecuteNonQuery();
                    }
                }
                // 提交事务
                trans.Commit();
                lblMsg.Text = String.Format("用户 '{0}' 创建成功。\n事务已提交。", txtUserName.Text);                            
            }
            catch(Exception inner) {
                // 发生错误，回滚事务
                if (trans != null) trans.Rollback();
                lblMsg.Text = String.Format("用户 '{0}' 创建失败。\n事务已回滚。\n详细信息：{1}", txtUserName.Text, inner.Message);
                //throw new Exception("创建用户失败。事务已回滚。", inner);
            }                       
        }
        // 重新加载 User 数据
        grdvUsers.DataBind();
    }

    protected void grdvUsers_RowDataBound(object sender, GridViewRowEventArgs e)
    {       
        // 加载每个 User 对应的 Roles
        DataList dlstRolesOfUser = e.Row.FindControl("dlstRolesOfUser") as DataList;
        if(dlstRolesOfUser == null) return;
       
        int userId = (int)grdvUsers.DataKeys[e.Row.RowIndex].Value;
       
        string sqlSelectRoleOfUser =
            "SELECT Role.RoleName FROM (Role INNER JOIN UserRole ON Role.RoleId = UserRole.RoleId) WHERE UserRole.UserId=?";
        OleDbDataAdapter da = new OleDbDataAdapter(sqlSelectRoleOfUser, connStr);
        da.SelectCommand.Parameters.Add("UserId", userId);
        DataTable dtRolesOfUser = new DataTable();
        da.Fill(dtRolesOfUser);
        dlstRolesOfUser.DataSource = dtRolesOfUser;
        dlstRolesOfUser.DataBind();       
    }
   
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>多对多写入实例——Access版本</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>      
        <h1>多对多写入实例——Access版本</h1>
        <h3>创建用户</h3>
        <table border="1">
            <tr>
                <td>
                    用户名：
                </td>
                <td>
                    <asp:TextBox ID="txtUserName" runat="server"></asp:TextBox>
                    <asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ControlToValidate="txtUserName"
                        Display="Dynamic" ErrorMessage="Required"></asp:RequiredFieldValidator></td>
            </tr>
            <tr>
                <td>
                    密码：
                </td>
                <td>
                    <asp:TextBox ID="txtPassword" runat="server"></asp:TextBox></td>
            </tr>
            <tr>
                <td>
                    角色：
                </td>
                <td>
                    <asp:CheckBoxList ID="chkRoles" runat="server" DataSourceID="AccessDataSource1" DataTextField="RoleName" DataValueField="RoleId" RepeatDirection="Horizontal"></asp:CheckBoxList><asp:AccessDataSource ID="AccessDataSource1" runat="server" DataFile="~/App_Data/DemoManyToMany.mdb"
                        SelectCommand="SELECT [RoleId], [RoleName] FROM [Role]"></asp:AccessDataSource>
                </td>
            </tr>
            <tr>
                <td>
                    强制发生错误：
                </td>
                <td>
                    <asp:CheckBox ID="chkGeneratError" runat="server" /></td>
            </tr>
            <tr>
                <td>
                </td>
                <td>
        <asp:Button ID="btnLogin" runat="server" Text="确定" OnClick="btnLogin_Click" /></td>

转载于:https://www.cnblogs.com/kangshifu/archive/2008/11/22/1338860.html

标签：ASP,Parameters,Text,cmd,UserId,RoleId,new,NET,ID
来源： https://blog.csdn.net/weixin_30767835/article/details/98113695