索引的使用

A. 使用简单索引
下面的示例为 authors 表的 au_id 列创建索引。


SET NOCOUNT OFF
USE pubs
IF EXISTS (SELECT name FROM sysindexes
     
WHERE name = 'au_id_ind')
  
DROP INDEX authors.au_id_ind
GO
USE pubs
CREATE INDEX au_id_ind
  
ON authors (au_id)
GO

B. 使用唯一聚集索引
下面的示例为 emp_pay 表的 employeeID 列创建索引,并且强制唯一性。因为指定了
CLUSTERED 子句,所以该索引将对磁盘上的数据进行物理排序。

SET NOCOUNT ON
USE pubs
IF EXISTS (SELECT * FROM INFORMATION_SCHEMA.TABLES
     
WHERE TABLE_NAME = 'emp_pay')
  
DROP TABLE emp_pay
GO
USE pubs
IF EXISTS (SELECT name FROM sysindexes
     
WHERE name = 'employeeID_ind')
  
DROP INDEX emp_pay.employeeID_ind
GO
USE pubs
GO
CREATE TABLE emp_pay
(
employeeID
int NOT NULL,
base_pay
money NOT NULL,
commission
decimal(2, 2) NOT NULL
)
INSERT emp_pay
  
VALUES (1, 500, .10)
INSERT emp_pay
  
VALUES (2, 1000, .05)
INSERT emp_pay
  
VALUES (3, 800, .07)
INSERT emp_pay
  
VALUES (5, 1500, .03)
INSERT emp_pay
  
VALUES (9, 750, .06)
GO
SET NOCOUNT OFF
CREATE UNIQUE CLUSTERED INDEX employeeID_ind
  
ON emp_pay (employeeID)
GO C. 使用简单组合索引 下面的示例为 order_emp 表的 orderID 列和 employeeID 列创建索引。 SET NOCOUNT ON
USE pubs
IF EXISTS (SELECT * FROM INFORMATION_SCHEMA.TABLES
     
WHERE TABLE_NAME = 'order_emp')
  
DROP TABLE order_emp
GO
USE pubs
IF EXISTS (SELECT name FROM sysindexes
     
WHERE name = 'emp_order_ind')
  
DROP INDEX order_emp.emp_order_ind
GO
USE pubs
GO
CREATE TABLE order_emp
(
orderID
int IDENTITY(1000, 1),
employeeID
int NOT NULL,
orderdate
datetime NOT NULL DEFAULT GETDATE(),
orderamount
money NOT NULL
)

INSERT order_emp (employeeID, orderdate, orderamount)
  
VALUES (5, '4/12/98', 315.19)
INSERT order_emp (employeeID, orderdate, orderamount)
  
VALUES (5, '5/30/98', 1929.04)
INSERT order_emp (employeeID, orderdate, orderamount)
  
VALUES (1, '1/03/98', 2039.82)
INSERT order_emp (employeeID, orderdate, orderamount)
  
VALUES (1, '1/22/98', 445.29)
INSERT order_emp (employeeID, orderdate, orderamount)
  
VALUES (4, '4/05/98', 689.39)
INSERT order_emp (employeeID, orderdate, orderamount)
  
VALUES (7, '3/21/98', 1598.23)
INSERT order_emp (employeeID, orderdate, orderamount)
  
VALUES (7, '3/21/98', 445.77)
INSERT order_emp (employeeID, orderdate, orderamount)
  
VALUES (7, '3/22/98', 2178.98)
GO
SET NOCOUNT OFF
CREATE INDEX emp_order_ind
  
ON order_emp (orderID, employeeID)

D. 使用
FILLFACTOR 选项
下面的示例使用
FILLFACTOR 子句,将其设置为 100FILLFACTOR100 将完全填满每一页,只有确定表中的索引值永远不会更改时,该选项才有用。

SET NOCOUNT OFF
USE pubs
IF EXISTS (SELECT name FROM sysindexes
     
WHERE name = 'zip_ind')
  
DROP INDEX authors.zip_ind
GO
USE pubs
GO
CREATE NONCLUSTERED INDEX zip_ind
  
ON authors (zip)
  
WITH FILLFACTOR = 100

E. 使用 IGNORE_DUP_KEY
下面的示例为 emp_pay 表创建唯一聚集索引。如果输入了重复的键,将忽略该
INSERTUPDATE 语句。

SET NOCOUNT ON
USE pubs
IF EXISTS (SELECT * FROM INFORMATION_SCHEMA.TABLES
     
WHERE TABLE_NAME = 'emp_pay')
  
DROP TABLE emp_pay
GO
USE pubs
IF EXISTS (SELECT name FROM sysindexes
     
WHERE name = 'employeeID_ind')
  
DROP INDEX emp_pay.employeeID_ind
GO
USE pubs
GO
CREATE TABLE emp_pay
(
employeeID
int NOT NULL,
base_pay
money NOT NULL,
commission
decimal(2, 2) NOT NULL
)
INSERT emp_pay
  
VALUES (1, 500, .10)
INSERT emp_pay
  
VALUES (2, 1000, .05)
INSERT emp_pay
  
VALUES (3, 800, .07)
INSERT emp_pay
  
VALUES (5, 1500, .03)
INSERT emp_pay
  
VALUES (9, 750, .06)
GO
SET NOCOUNT OFF
GO
CREATE UNIQUE CLUSTERED INDEX employeeID_ind
  
ON emp_pay(employeeID)
  
WITH IGNORE_DUP_KEY

F. 使用 PAD_INDEX 创建索引
下面的示例为 authors 表中的作者标识号创建索引。没有 PAD_INDEX 子句,SQL Server 将创建填充
10% 的叶级页,但是叶级之上的页几乎被完全填满。使用 PAD_INDEX 时,中间级页也填满 10%



说明  如果没有指定 PAD_INDEX,唯一聚集索引的索引页上至少会出现两项。



SET NOCOUNT OFF
USE pubs
IF EXISTS (SELECT name FROM sysindexes
     
WHERE name = 'au_id_ind')
  
DROP INDEX authors.au_id_ind
GO
USE pubs
CREATE INDEX au_id_ind
  
ON authors (au_id)
  
WITH PAD_INDEX, FILLFACTOR = 10

G. 为视图创建索引
下面的示例将创建一个视图,并为该视图创建索引。然后,引入两个使用该索引视图的查询。


USE Northwind
GO

--Set the options to support indexed views.
SET NUMERIC_ROUNDABORT OFF
GO
SET ANSI_PADDING,ANSI_WARNINGS,CONCAT_NULL_YIELDS_NULL,ARITHABORT,QUOTED_IDENTIFIER,ANSI_NULLS ON
GO

--Create view.
CREATE   VIEW V1
WITH   SCHEMABINDING
AS
   SELECT SUM(UnitPrice*Quantity*(1.00-Discount)) AS Revenue, OrderDate, ProductID, COUNT_BIG(*) AS COUNT
   FROM   dbo.[Order Details] od, dbo.Orders o
  
WHERE   od.OrderID=o.OrderID
  
GROUP BY   OrderDate, ProductID
GO

--Create index on the view.
CREATE UNIQUE CLUSTERED INDEX IV1 ON V1 (OrderDate, ProductID)
GO

--This query will use the above indexed view.
SELECT SUM(UnitPrice*Quantity*(1.00-Discount)) AS Rev, OrderDate, ProductID
FROM   dbo.[Order Details] od, dbo.Orders o
WHERE   od.OrderID=o.OrderID AND ProductID in (2, 4, 25, 13, 7, 89, 22, 34)
  
AND OrderDate >= '05/01/1998'
GROUP BY OrderDate, ProductID
ORDER BY Rev DESC

--This query will use the above indexed view.
SELECT  OrderDate, SUM(UnitPrice*Quantity*(1.00-Discount)) AS Rev
FROM   dbo.[Order Details] od, dbo.Orders o
WHERE   od.OrderID=o.OrderID AND DATEPART(mm,OrderDate)= 3
   AND DATEPART(yy,OrderDate) = 1998
GROUP BY OrderDate
ORDER BY OrderDate ASC
 

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