需要帮助的SQL Server 2005 [英] need help for sql server 2005

问题描述

朋友

我是新手，所以我不知道如何开始我的问题?我需要有关外键约束的帮助，或者说加入2个表.请为我找到一个源代码.

Ridhi Shrestha

Friends

I am new, so I don''t konw how to start my question ? I need help for foreign key constraint or say join 2 tables. please find me a source code for this.

Ridhi Shrestha

推荐答案

Ridhi，

http://www.java2s.com/Code/SQLServer/Constraints/Howtouseforeignkeyconstraints.htm [ ^ ]

http://www.1keydata.com/sql/sql-foreign-key.htm [ ^ ]

http://www.sql-tutorial.net [

Hi Rid

http://www.java2s.com/Code/SQLServer/Constraints/Howtouseforeignkeyconstraints.htm[^]

http://www.1keydata.com/sql/sql-foreign-key.htm[^]

http://www.sql-tutorial.net[^]

Refer those links.

In my suggestion first you can learn basics of sql.There are lot of books available in online.Search in google.

Cheers :)

好吧，外键并不是真正的联接"表，它们是关联"表，也是创建外键约束有用的主要原因表中的表用作检查机制，以防止通过诸如删除表等之类的动作而导致相关表中的数据的动作

以下是显示带有外键缺点的表的基本sql代码.

ok first, Foreign keys do not really ''join'' tables, they rather ''relate'' tables and the main reason why it is useful to create foreign key constraint in a table is serve as a checking mechanism to prevent actions that will cause data in a related table through an action like dropping a table etc

Below is a basic sql code showing a table with a foreign key cons.

CREATE TABLE Orders
(
O_Id int NOT NULL,
OrderNo int NOT NULL,
P_Id int,
PRIMARY KEY (O_Id),
FOREIGN KEY (P_Id) REFERENCES Persons(P_Id)
)

但是在连接两个表(以某种扩展名)时，您将不得不使用sql joins，如果您还不了解sql，我将推荐您使用google进行阅读. sql union ..:)

but in joining two tables (in a sort of extension), then you would have to use sql joins, which if you dont have any knowledge of yet, I would edge you to do google it up and read..Also check up the sql union..:)

Ridhi Shrestha，

遵循以下链接

http://www.1keydata.com/sql/sql-foreign-key.html

http://www.mssqlcity.com/Articles/General/using_constraints.htm

Hi Ridhi Shrestha,

follow the below links

http://www.1keydata.com/sql/sql-foreign-key.html

http://www.mssqlcity.com/Articles/General/using_constraints.htm


Table CUSTOMER
column name characteristic
------------ ------------
SID int Primary Key
Last_Name varchar(50)
First_Name varchar(50)

Table ORDERS

CREATE TABLE ORDERS
(Order_ID integer primary key,
Order_Date datetime,
Customer_SID int references CUSTOMER(SID),
Amount money)


Cheers :)

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