㈠ 当有大量数据时，Access如何让两个表之间用ID（自动编号）字段相关联。
可以给你这么解释，A和B在一起，写个语句就是C，你这样的C是不用必须存在的
你看我这么写，就能给你得到C
sql">selectA.id,B.名称,A.类别fromA,BwhereA.id=B.a_id
实际中，C可以以另一种形式存在，比如你要记录各个名称东西的数量，C表可以这样
AID BID 数量
1 1 10
2 1 100
3 3 1000
㈡ 数据库中“关联字段”是什么意思能否举几个形象的例子。我不是计算机专业，最好不要用过多的专业术语
关联字段白话点，就是如果想将两个表的数据关联起来，就需要2个表各有1个字段将2个表关联起来，这个字段就是关联字段
打个比方来说
一个订单主表--字段：订单单号、客户姓名、客户地址
一个订单从表--字段：订单单号、订购产品、订购价格
如果想查询具体订单信息，就需要将订单主表和订单从表关联起来，怎么关联？就需要用订单单号，因为这2个表都有订单单号，且订单单号相同。
不明白再问我吧，，手打，望采纳，，，，
㈢ 怎样直接通过登陆ID关联到数据库覆值
using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.Adapters;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using AC.GlobalClass;
using System.Data.SqlClient;
using AC.CreateImage;
public partial class _login : System.Web.UI.Page
{
private readonly string SQLCONNECTIONSTRING = ConfigurationManager.AppSettings["SQLCONNECTIONSTRING"].ToString();
protected void Page_Load(object sender, EventArgs e)
{
Page.Title = "登录";
if (this.Session["username"] != "" && this.Session["username"] != null)
{
Response.Redirect("service/support.aspx");
}
}
protected void IB1_Click(object sender, EventArgs e)
{
string strloginid = LoginID.Text;
string strpassword = PassWord.Text;
string strQuery = "select count(*) from Customers where LoginID='" + strloginid + "'";
SqlConnection myconn = new SqlConnection(SQLCONNECTIONSTRING);
SqlCommand mycomm = new SqlCommand(strQuery, myconn);
myconn.Open();
int s = Convert.ToInt16(mycomm.ExecuteScalar());
myconn.Close();
if (s == 0)
{
ClientScript.RegisterStartupScript(typeof(string), "aa", " <script>alert('用户名不存在!'); </script>");
return;
}
strQuery = "select PassWord from Customers where LoginID='" + strloginid + "'";
mycomm = new SqlCommand(strQuery, myconn);
myconn.Open();
string pass = Convert.ToString(mycomm.ExecuteScalar());
myconn.Close();
if (pass != strpassword)
{
ClientScript.RegisterStartupScript(typeof(string), "aa1", " <script>alert('密码错误!'); </script>");
return;
}
strQuery = "select flag from Customers where LoginID='" + strloginid + "'";
mycomm = new SqlCommand(strQuery, myconn);
myconn.Open();
string flag = Convert.ToString(mycomm.ExecuteScalar());
myconn.Close();
if (flag != "1")
{
Response.Redirect("unflag.aspx");
}
this.Session["username"] = strloginid;
strQuery = "select peoplename from Customers where LoginID='" + strloginid + "'";
mycomm = new SqlCommand(strQuery, myconn);
myconn.Open();
string strname = Convert.ToString(mycomm.ExecuteScalar());
myconn.Close();
strQuery = "select name from Customers where LoginID='" + strloginid + "'";
mycomm = new SqlCommand(strQuery, myconn);
myconn.Open();
string strdname = Convert.ToString(mycomm.ExecuteScalar());
myconn.Close();
strQuery = "select sex from Customers where LoginID='" + strloginid + "'";
mycomm = new SqlCommand(strQuery, myconn);
myconn.Open();
string strsex = Convert.ToString(mycomm.ExecuteScalar());
myconn.Close();
strQuery = "select phone from Customers where LoginID='" + strloginid + "'";
mycomm = new SqlCommand(strQuery, myconn);
myconn.Open();
string strphone = Convert.ToString(mycomm.ExecuteScalar());
myconn.Close();
strQuery = "select QQ from Customers where LoginID='" + strloginid + "'";
mycomm = new SqlCommand(strQuery, myconn);
myconn.Open();
string strQQ = Convert.ToString(mycomm.ExecuteScalar());
myconn.Close();
strQuery = "select address from Customers where LoginID='" + strloginid + "'";
mycomm = new SqlCommand(strQuery, myconn);
myconn.Open();
string stradd = Convert.ToString(mycomm.ExecuteScalar());
myconn.Close();
strQuery = "select email from Customers where LoginID='" + strloginid + "'";
mycomm = new SqlCommand(strQuery, myconn);
myconn.Open();
string stremail = Convert.ToString(mycomm.ExecuteScalar());
myconn.Close();
this.Session["username"] = strloginid;
this.Session["name"] = strname;
this.Session["dname"] = strdname;
this.Session["sex"] = strsex;
this.Session["phone"] = strphone;
this.Session["QQ"] = strQQ;
this.Session["address"] = stradd;
this.Session["email"] = stremail;
Response.Redirect("service/support.aspx");
}
}
㈣ 数据库中不同的表，怎样设置两个id关联
方法一：传统方法select m.id,m.name,m.class,m.xid,x.phone,x.address from member m,xinxi x where m.id=x.id;
方法二：自然连接select * from member natural join xinxi;
方法三：直接连接select x.id,m.name,m.class,m.xid,x.phone,x.address from member m join xinxi x on m.id=x.id;
㈤ 在两个数据库里查询信息，用id号联系起来，显示在表格中，该如何做呢求实例或相关博文的链接
先定义一个ResultSet rs对象 把查询后的ResultSet集复制给rs
然后通过调用rs的next（）方法将指针向下移动 实现循环显示数据 数据的显示是调用rs的getXxxx(列名或列号) 其中Xxxx是数据类型
如while(rs.next()){out.print(rs.getString(列名))}
㈥ 数据库两个表靠id关联，现在要条件查找数据。
select 姓名
from a, b
where a.id=b.id
and 性别='男'
and 班级<>'1班'
㈦ mysql怎么让2个表关联起来
方法和操作步骤如下：
1、首先，创建一个测试表，如下图所示，然后进入下一步。
㈧ 在MYSQL数据库里如何建立两个表的关联
1、首先我们打开Workbench创一个建数据库（这里都使用闪电1执行选定命令行)。
㈨ sql数据库中都采用ID一级级关联，如何自动匹配ID通过EXCEL批量导入数据
1、添加jxl.jarmysql-connector-java.1.7-bin.jar包到项目的lib目录下
2、Excel文件目录:D://book.xls
3、数据库名：javenforexcel
4、表名:stu
5、编写类：连接mysql的字符串方法、插入的方法、实体类