create table student ( id int not null, name varchar2(50), sex varchar2(25), birthday varchar2(225), createtime timestamp, primary key(id), t_id int FOREIGN KEY REFERENCES teacher(t_id) //一个外键 ); <!--可建立联合主键,例如primary key(id,name),这样id和name都是主键,且id不允许重...
--删除主键 alter table 表名drop constraint 主键名 --添加主键 alter table 表名add constraint 主键名 primary key(字段名1,字段名2……) --添加非聚集索引的主键 alter table 表名add constraint 主键名 primary key NONCLUSTERED(字段名1,字段名2……) 新建表: create table [表名] ( [自动编号字段]...
SQL Server怎么建立联合主键 可直接用sql语句。 一种是在建表时就写出,语句如下: Create Table 表名 (字段名1 Int Not Null, 字段名2 nvarchar(13) Not Null Primary Key (字段名1, 字段名2), 字段名3……… 字段名N……… ) 另一种是在建表后更改,语句如下: ALTER TABLE 表名 WITH NOCHECK ADD C...
语句:create index [复合索引名] on [表名](列名1 asc|desc, 列名2 asc|desc) with(drop_existing = on) 例如:create index IX_com_Book_IDName on Book (ID,Name) 4.创建唯一索引 语句:create unique index index_name on table_name (column ASC|DESC[,...])with (drop_existing = on) 例如:c...
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...
有关SQL Server 和 Azure SQL 平台,请访问 CREATE TABLE,并选择所需的产品版本。有关 Microsoft Fabric 中的 SQL 数据库,请参阅 CREATE TABLE。有关 Microsoft Fabric 中的仓库的参考,请访问 CREATE TABLE (Fabric)。 备注 Azure Synapse 分析中的无服务器 SQL 池仅支持外部表和临时表。 Transact-SQL 语法约定...
] referenced_table_name [ ( ref_column ) ] | CHECK ( logical_expression ) } <table_constraint> ::= [ CONSTRAINT constraint_name ] { { PRIMARY KEY | UNIQUE } { NONCLUSTERED ( column_name [ ASC | DESC ] [ ,... n ]) | NONCLUSTERED HASH ( column_name [ ,... n ] ) WITH ...
] referenced_table_name [ ( ref_column ) ] | CHECK ( logical_expression ) } <table_constraint> ::= [ CONSTRAINT constraint_name ] { { PRIMARY KEY | UNIQUE } { NONCLUSTERED ( column_name [ ASC | DESC ] [ ,... n ]) | NONCLUSTERED HASH ( column_name [ ,... n ] ) WITH ...
] referenced_table_name [ ( ref_column ) ] | CHECK ( logical_expression ) } <table_constraint> ::= [ CONSTRAINT constraint_name ] { { PRIMARY KEY | UNIQUE } { NONCLUSTERED ( column_name [ ASC | DESC ] [ ,... n ]) | NONCLUSTERED HASH ( column_name [ ,... n ] ) WITH ...
When a new row is added to the table, SQL Server Compact provides a unique, incremental value for the column. Identity columns are generally used in conjunction with PRIMARY KEY constraints to serve as the unique row identifier for the table. The IDENTITY property can be assigned only to int...