Define a primary key in the SQL Server Database Engine by using SQL Server Management Studio or Transact-SQL.
支援的條件約束包括 PRIMARY KEY、 UNIQUE與CHECK。 如需資料表的詳細資訊,請參閱 CREATE TABLE (Transact-SQL)。 <computed_column_definition> 將計算資料行運算式定義為使用者定義資料表類型中的資料行。 如需資料表的詳細資訊,請參閱 CREATE TABLE (Transact-SQL)。 定義使用者定義資料表類型上的資料表條件...
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 foreign key (eid) re...
] type_name [ (precision [ , scale ]) ] <column_constraint> ::= [ CONSTRAINT constraint_name ] { { PRIMARY KEY | UNIQUE } { NONCLUSTERED | NONCLUSTERED HASH WITH ( BUCKET_COUNT = bucket_count ) } [ ( <column_name> [ ,... n ] ) ] | [ FOREIGN KEY ] REFERENCES [ schema_...
A unique index, UNIQUE constraint, or PRIMARY KEY constraint cannot be created if duplicate key values exist in the data. A unique nonclustered index can contain included nonkey columns. For more information, see Create an index with included columns....
定义用户定义表类型的表约束。 支持的约束包括 PRIMARY KEY、 UNIQUE和CHECK。 <index_option> 指定对唯一聚集索引或唯一非聚集索引执行多行插入操作时出现重复键值的错误响应。 有关索引选项的详细信息,请参阅 CREATE INDEX (Transact-SQL)。 INDEX index_name [ CLUSTERED |NONCLUSTERED ] ( column_name [ ASC...
In table-valued user-defined functions, the PRIMARY KEY constraint can be created on only one column per table. PRIMARY KEY can't be specified for CLR table-valued functions. UNIQUE A constraint that provides entity integrity for a specified column or columns through a unique index. A table ...
] type_name [ (precision [ , scale ]) ] <column_constraint> ::= [ CONSTRAINT constraint_name ] { { PRIMARY KEY | UNIQUE } { NONCLUSTERED | NONCLUSTERED HASH WITH ( BUCKET_COUNT = bucket_count ) } [ ( <column_name> [ ,... n ] ) ] | [ FOREIGN KEY ] REFERENCES [ schema_...
] type_name [ (precision [ , scale ]) ] <column_constraint> ::= [ CONSTRAINT constraint_name ] { { PRIMARY KEY | UNIQUE } { NONCLUSTERED | NONCLUSTERED HASH WITH ( BUCKET_COUNT = bucket_count ) } [ ( <column_name> [ ,... n ] ) ] | [ FOREIGN KEY ] REFERENCES [ schema_...
(5) CONSTRAINT P_STUDENT PRIMARY KEY, SNAME CHAR(6) NOT NULL, SSEX CHAR(2) DEFAULT '男' CONSTRAINT C_SSEX CHECK( SSEX IN ('男','女')), SAGE NUMERIC(2) DEFAULT 20, SDEPT CHAR(10) ); CREATE TABLE COURSE ( CNO NUMERIC(2) CONSTRAINT P_COURSE PRIMARY KEY, CNAME CHAR(10) NOT ...