6.默认约束 --DefaultALTERTABLEdbo.OrdersADDCONSTRAINTDFT_Orders_ordertsDEFAULT(SYSDATETIME())FORorderts;--CleanupDROPTABLEdbo.Orders, dbo.Employees;
ADD CONSTRAINT CK_Gender CHECK (Gender = 0 OR Gender = 1), ADD CONSTRAINT DF_Gender DEFAULT (0) FOR Gender; ``` 为`OrderInfo` 表添加外键约束和默认值约束: ```sql ALTER TABLE OrderInfo ADD CONSTRAINT FK_Userld FOREIGN KEY (Userld) REFERENCES UserInfo (Userld), ADD CONSTRAINT FK_Commodit...
alter table 表名 add constraint 约束名 check (字段 between 1 and 100 ) ---添加外键约束(主表stuInfo和从表stuMarks建立关系,关联字段为stuNo) alter table 从表 add constraint 约束名 foreign key(关联字段) references 主表(关联字段) --sql server中删除约束的语句是: alter table 表名 drop constrai...
CONSTRAINT_TABLE_USAGE DOMAIN_CONSTRAINTS DOMAIN KEY_COLUMN_USAGE PARAMETER REFERENTIAL_CONSTRAINTS ROUTINE_COLUMNS ROUTINES SCHEMATA TABLE_CONSTRAINTS TABLE_PRIVILEGES TABLES VIEW_COLUMN_USAGE VIEW_TABLE_USAGE VIEWS Prosedur tersimpan sistem Tabel sistem Referensi Transact-SQL (T-SQL) xQuery Undu...
When you create a primary key, SQL Server enforces the constraint behind the scenes by creating a unique index on that column and using the primary key column or columns as the keys of the index. 当你创建一个主键时,SQL Server强制在幕后对这个列创建唯一性索引,并使用主键列作为索引的键。
1:--创建新表2:use MyDemo3:CREATETABLE[dbo].[Employees](4:[empid][int]IDENTITY(1,1)NOTNULL,5:[empname][nvarchar](100)NULL,6:[deptid][int]NULL,7:[Salary][float]NULL,8:CONSTRAINT[PK_Employees]PRIMARYKEYCLUSTERED9:([empid]ASC)10:WITH11:(PAD_INDEX=OFF,STATISTICS_NORECOMPUTE=OFF,IGNORE...
Satu-satunya cara yang dapat diandalkan untuk menemukan skema objek adalah dengan mengkueri sys.objects tampilan katalog. CONSTRAINT_NAME nama sysname Nama batasan. CHECK_CLAUSE nvarchar(4000) Teks aktual dari pernyataan definisi Transact-SQL.
@@error值都会变 select @@language;--返回当前所用语言的名称 select @@rowcount;--返回受上一语句影响的行数 select @@servername;--返回运行 SQL Server 的本地服务器的名称 select @@trancount;--返回当前连接的活动事务数 select @@max_connections;--返回 SQL Server 实例允许同时进行的最大用户连接数...
constraint Sale_Prim Primary Key(Date,BNo) ) 1. 2. 3. 4. 5. 6. 7. 8. 创建XXX通常都对应于create语句: 创建数据库:create database db_name on ... log on ... 创建数据表:create table table_name (Attributes) 创建索引:create index index_name on tb_name(Attributes) ...
,Filename = 'E:\SQLDataFile\memoryDB_log.ldf' ) GO CREATE TABLE MemorySchemaAndData ( id int NOT NULL, c1 nchar(1) NOT NULL, CONSTRAINT PK_MemorySchemaAndData PRIMARY KEY NONCLUSTERED HASH (id) WITH (BUCKET_COUNT = 150000) ) WITH (MEMORY_OPTIMIZED = ON, DURABILITY =...