SQL نسخ CREATE TABLE [Production].[TransactionHistoryArchive1] ( CustomerID UNIQUEIDENTIFIER DEFAULT NEWSEQUENTIALID(), TransactionID INT IDENTITY(1, 1) NOT NULL, CONSTRAINT PK_TransactionHistoryArchive1_CustomerID PRIMARY KEY NONCLUSTERED (CustomerID) ); Now add the clustered index. SQL ...
Use SQL Server Management Studio In Object Explorer, right-click the table to which you want to add a unique constraint, and selectDesign. InTable Designer, select the row selector for the database column you want to define as the primary key. If you want to select multiple columns, hold...
2.2)外键(约束)创建(不推荐使用,一般不进行外键约束,只进行外键约定): alert table 主键表名 add constraint FK_ID(外键名称) foreign key(外键字段名) references 外表表名(主键字段名) 2.3)外键出现的情况: 补充: 在创建表的时候,表和表之间可能会存在的业务关系(关联关系),这时会产生外键。 关联关系中存在...
CREATE TABLE Persons ( Id_P int NOT NULL, LastName varchar(255) NOT NULL, FirstName varchar(255), Address varchar(255), City varchar(255),CONSTRAINTuc_PersonIDPRIMARYKEY (Id_P,LastName)) SQL PRIMARY KEY Constraint on ALTER TABLE 如果在表已存在的情况下为 "Id_P" 列创建 PRIMARY KEY 约束...
2)PRIMARY KEY(两种写法) --注:如果使用ALTER TABLE语句添加主键,必须把主键列声明为不包含NULL值(在表首次创建时)。 altertablePersonsaddprimarykey(id_p);altertablePersonsadd constraintuc_PersonIDprimarykey(id_p, lastname); 3)FOREIGN KEY(两种写法) ...
Creates an IPrimaryKeyConstraint object that is associated with the specified IRelationalIndex object. 命名空间: Microsoft.SqlServer.Management.SqlParser.MetadataProvider 程序集: Microsoft.SqlServer.Management.SqlParser(在 Microsoft.SqlServer.Management.SqlParser.dll 中) 语法 C# 复制 IPrimaryKeyConstraint ...
PRIMARY KEY or UNIQUE constraint When you create a PRIMARY KEY constraint, a unique clustered index on the column or columns is automatically created if a clustered index on the table does not already exist and you do not specify a unique nonclustered index. The primary key column cannot ...
id int identity not null primary key, customerid int not null foreign key references customer(id), orderdate smalldatetime not null, eid int not null ) 注意:这个表的外键必须是另一个表的主键! 在现有表上添加外键 alter table orders add constraint fk_employee_creator_order ...
When you create aPRIMARY KEYconstraint, a unique clustered index on the column or columns is automatically created if a clustered index on the table doesn't already exist and you don't specify a unique nonclustered index. The primary key column can't allowNULLvalues. ...
When you create aPRIMARY KEYconstraint, a unique clustered index on the column or columns is automatically created if a clustered index on the table doesn't already exist and you don't specify a unique nonclustered index. The primary key column can't allowNULLvalues. ...