Question

我尝试了两个表的查询，但是如果我想为很多表做这个怎么做呢？

cmd.CommandText = "SELECT *  FROM assignments 
                   inner join Customers on assignments.Customer_ID = customers.Customer_ID";
//assignments and customers are tables

Answer 1

考虑代理商，客户，订单作为您的表格＆amp;你必须加入他们。

SELECT 
    a.ord_num,
    b.cust_name,
    a.cust_code,  
    c.agent_code,
    b.cust_city  
FROM agents c, customer b, orders a  
WHERE b.cust_city = c.working_area  
    AND a.cust_code = b.cust_code  
    AND a.agent_code = c.agent_code;

问候！

Answer 2

这里我举一个例子。您可以创建如下的查询：

select 
    * 
from tblA a 
     inner join tblB b 
         on a.id = b.id 
     inner join tblC 
         on a.id = c.id 
     inner join tblD 
         on a.id = d.id

Answer 3

如果您使用的是SQL管理工作室，请右键单击并选择＆＃34;编辑器中的设计查询＆＃34;。这是加入表格的最简单方法（它的视觉效果）

Answer 4

可能会帮助你

SELECT * FROM assignments AS a, customers AS c WHERE a.Customer_ID = c.Customer_ID;

如何加入多个表？

4 个答案: