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移動硬碟隱藏文件 2022-06-30 15:14:51
海綿視頻存儲位置 2022-06-30 15:09:08

資料庫通過id關聯

發布時間: 2022-05-19 15:48:48

㈠ 當有大量數據時,Access如何讓兩個表之間用ID(自動編號)欄位相關聯。

可以給你這么解釋,A和B在一起,寫個語句就是C,你這樣的C是不用必須存在的

你看我這么寫,就能給你得到C

sql">selectA.id,B.名稱,A.類別fromA,BwhereA.id=B.a_id

實際中,C可以以另一種形式存在,比如你要記錄各個名稱東西的數量,C表可以這樣


AID BID 數量

1 1 10

2 1 100

3 3 1000

資料庫中「關聯欄位」是什麼意思能否舉幾個形象的例子。我不是計算機專業,最好不要用過多的專業術語

關聯欄位白話點,就是如果想將兩個表的數據關聯起來,就需要2個表各有1個欄位將2個表關聯起來,這個欄位就是關聯欄位
打個比方來說
一個訂單主表--欄位:訂單單號、客戶姓名、客戶地址
一個訂單從表--欄位:訂單單號、訂購產品、訂購價格
如果想查詢具體訂單信息,就需要將訂單主表和訂單從表關聯起來,怎麼關聯?就需要用訂單單號,因為這2個表都有訂單單號,且訂單單號相同。
不明白再問我吧,,手打,望採納,,,,

㈢ 怎樣直接通過登陸ID關聯到資料庫覆值

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 = "登錄";
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('用戶名不存在!'); </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('密碼錯誤!'); </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 資料庫中不同的表,怎樣設置兩個id關聯

方法一:傳統方法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:自然連接select * from member natural join xinxi;
方法三:直接連接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 在兩個資料庫里查詢信息,用id號聯系起來,顯示在表格中,該如何做呢求實例或相關博文的鏈接

先定義一個ResultSet rs對象 把查詢後的ResultSet集復制給rs
然後通過調用rs的next()方法將指針向下移動 實現循環顯示數據 數據的顯示是調用rs的getXxxx(列名或列號) 其中Xxxx是數據類型
如while(rs.next()){out.print(rs.getString(列名))}

㈥ 資料庫兩個表靠id關聯,現在要條件查找數據。

select 姓名
from a, b
where a.id=b.id
and 性別='男'
and 班級<>'1班'

㈦ mysql怎麼讓2個表關聯起來

方法和操作步驟如下:

1、首先,創建一個測試表,如下圖所示,然後進入下一步。

㈧ 在MYSQL資料庫里如何建立兩個表的關聯

1、首先我們打開Workbench創一個建資料庫(這里都使用閃電1執行選定命令行)。

㈨ sql資料庫中都採用ID一級級關聯,如何自動匹配ID通過EXCEL批量導入數據

1、添加jxl.jarmysql-connector-java.1.7-bin.jar包到項目的lib目錄下­

2、Excel文件目錄:D://book.xls

3、資料庫名:javenforexcel

4、表名:stu

5、編寫類:連接mysql的字元串方法、插入的方法、實體類­­