PRIMARY KEY 约束默认为 CLUSTERED;UNIQUE 约束默认为 NONCLUSTERED。 如果表中已存在聚集约束或索引,那么在 ALTER TABLE 中就不能指定 CLUSTERED。如果表中已存在聚集约束或索引,PRIMARY KEY 约束默认为 NONCLUSTERED。最大区别在于clustered是物理上实现数据排序,并且同一个表里只能有一个clustered索引,而nonclustered是...
1USE[pratice]2GO3CREATETABLE#tempPKCL4(5IDINTPRIMARYKEYCLUSTERED--聚集索引6)789---10USE[pratice]11GO12CREATETABLE#tempPKNCL13(14IDINTPRIMARYKEYNONCLUSTERED--非聚集索引15)161718DROPTABLE[#tempPKCL]19DROPTABLE[#tempPKNCL] 如果不加NONCLUSTERED和CLUSTERED关键字,默认建的是聚集索引 而一个聚集索引里...
bookId int identity(1,1) primary key, bookName varchar(20) not null, bookNotes varchar(100) null ) --创建一个读者表-- create table Reader( readId int identity(1,1) primary key, readerName varchar(20) not null, ) --创建一个借书表(没有主键)-- create table BookAndReader( bookId in...
[LastModifyId] [int] NULL CONSTRAINT [PK_SysUser] PRIMARY KEY CLUSTERED ( [Id] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, OPTIMIZE_FOR_SEQUENTIAL_KEY = OFF) ON [PRIMARY] ) ON [PRIMARY] GO GO S...
ALTER TABLE Atest ADD MainId int identity(1,1) PRIMARY KEY; 2.主键为GUID ALTER TABLE dbo.Atest ADD MainId uniqueidentifier NOT NULL CONSTRAINT DF_Atest_MainId DEFAULT newid() GO ALTER TABLE dbo.Atest ADD CONSTRAINT PK_Atest PRIMARY KEY CLUSTERED ( MainId ) WITH( STATISTICS_NORECOMPUTE ...
CREATE PRIMARY KEY CLUSTERED INDEX IX_Employee_ID ON Employee (ID); 或者 CREATE PRIMARY KEY NONCLUSTERED INDEX IX_Employee_ID ON Employee (ID); 使用索引 当查询涉及到索引列时,SQL Server会自动使用索引来加速查询,以下查询将使用上面创建的非聚集索引IX_Employee_FirstName: ...
(20) NULL, CONSTRAINT [id] PRIMARY KEY CLUSTERED( [id] ASC ) ON [PRIMARY]) go...
( // OrderID int NOT NULL // ProductID int NOT NULL // CONSTRAINT PK_OrderDetails // PRIMARY KEY CLUSTERED (OrderID, ProductID), // UnitPrice money NOT NULL, // Quantity int NOT NULL, // Discount decimal(2,2) NOT NULL // DEFAULT 0 // ) // HRESULT CreatePrimaryKey ( IIndex...
[Sql][nvarchar](max)NOTNULL,[CheckType][nvarchar](400)NOTNULLCONSTRAINT[PK_ZL_AuthorityCheckInfo_TB]PRIMARY KEY CLUSTERED([AuthorityCheckName]ASC)WITH(PAD_INDEX=OFF,STATISTICS_NORECOMPUTE=OFF,IGNORE_DUP_KEY=OFF,ALLOW_ROW_LOCKS=ON,ALLOW_PAGE_LOCKS=ON)ON[PRIMARY])ON[PRIMARY]TEXTIMAGE_ON[PRIMARY]...
NATIONAL | NOCHECK | NONCLUSTERED | NOT | NULL | NULLIF OF | OFF | OFFSETS | ON | OPEN | OPENDATASOURCE | OPENQUERY | OPENROWSET OPENXML | OPTION | OR | ORDER | OUTER | OVER PERCENT | PIVOT | PLAN | PRECISION | PRIMARY | PRINT | PROC ...