Use SQL Server Management StudioCreate a primary keyIn Object Explorer, right-click the table to which you want to add a unique constraint, and select Design. In Table Designer, select the row selector for the database column you want to define as the primary key. If you want to select...
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...
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....
You can create a clustered index on a column other than primary key column if a nonclustered primary key constraint was specified. Limitations When a clustered index structure is created, disk space for both the old (source) and new (target) structures is required in their respective files and...
You can create a unique constraint in SQL Server by using SQL Server Management Studio or Transact-SQL to ensure no duplicate values are entered in specific columns that don't participate in a primary key. Creating a unique constraint automatically creates a corresponding unique index....
You can create a clustered index on a column other than primary key column if a nonclustered primary key constraint was specified. Limitations When a clustered index structure is created, disk space for both the old (source) and new (target) structures is required in their respective files and...
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 ...
add constraint pk_employeeid primary key (id) 4:外键约束 外键约束用在确保数据完整性和两个表之间的关系上 先看例子 create table orders ( id int identity not null primary key, customerid int not null foreign key references customer(id), ...
] 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 ...