create table child (i1 int not null primary key, i2 int, i3 int); create table grandchild (i1 int not null primary key, i2 int, i3 int); alter table parent add constraint fkp1 foreign key (i2) references grandparent; alter table parent2 add constraint fkp2 foreign key (i2) refe...
SQL定义功能中,用CREATE TABLE建立表时,FOREIGN KEY...REFERENCES…短语的含义是A.说明主关键字B.建立表之间的联系C.说明有效性规则
本文介绍如何使用 SQL Server Management Studio 或 Transact-SQL 在 SQL Server 中创建外键关系。 当希望将一个表的行与另一个表的行相关联时,您可在这两个表之间创建关系。 权限 使用外键创建新表需要在数据库中具有CREATE TABLE权限,并对在其中创建表的架构具有ALTER SCHEMA权限。
{PRIMARYKEY|UNIQUE} [CLUSTERED|NONCLUSTERED] [WITHFILLFACTOR= fillfactor |WITH(< index_option >[ , ...n ] ) ] [ON{partition_scheme_name(partition_column_name) | filegroup |"default"} ] | [FOREIGNKEY]REFERENCES[schema_name. ]referenced_table_name[ (ref_column) ] [ONDELETE{NOACTION|...
A standard user-defined table can have up to 1,024 columns. The number of rows in the table is limited only by the storage capacity of the server. You can assign properties to the table and to each column in the table to control the data that is allowed and other properties. For ...
(partition_column_name) | filegroup | "default" } ] | FOREIGN KEY ( column_name [ ,... n ] ) REFERENCES referenced_table_name [ ( ref_column [ ,... n ] ) ] [ ON DELETE { NO ACTION | CASCADE | SET NULL | SET DEFAULT } ] [ ON UPDATE { NO ACTION | CASCADE | SET NULL...
https://blog.csdn.net/dengguawei0519/article/details/101315699 1。找到引用这个表外键名称 SELECT * FROM sys.foreign_keys WHERE referenced_object_id=OBJECT_ID('User'); 删除外键 删除掉引用表的外键 ALTER TABLE dbo.XX DROP constraint FK_User_XX...
CREATE TABLE TestBatch (ColA INT PRIMARY KEY, ColB CHAR(3)); GO INSERT INTO TestBatch VALUES (1, 'aaa'); INSERT INTO TestBatch VALUES (2, 'bbb'); INSERT INTO TestBatch VALUSE (3, 'ccc'); -- Syntax error. GO SELECT * FROM TestBatch; -- Returns no rows. GO In the followi...
SQL Server数据库 使用SQL语句进行的一系列操作 1、建库 最简单的创建数据库的方式: createdatabase 数据库名 这种方式可以快速地创建数据库,唯一的缺点就是创建数据库的路径为当前SQLserver的安装目录下C:\Program Files\Microsoft SQL Server\MSSQL12.MSSQLSERVER\MSSQL\DATA中,不方便查找。
SQL FOREIGN KEY on ALTER TABLE To create aFOREIGN KEYconstraint on the "PersonID" column when the "Orders" table is already created, use the following SQL: MySQL / SQL Server / Oracle / MS Access: ALTERTABLEOrders ADDFOREIGNKEY(PersonID)REFERENCESPersons(PersonID); ...