索引与视图

索引

CREATE CLUSTERED INDEX SNUM ON STUDENT(SNO DESC)
exec sp_helpindex student/*查询索引的创建情况，以查看存储过程的方式查看创建的索引格式如下：sp_helpindex [@objname=] 'name'*/
exec stu_all/*由于创建的是降序索引所以查询的结果以降序显示*/
/*创建唯一索引*/
CREATE UNIQUE INDEX SUNIQUE ON STUDENT(SNO DESC)
CREATE NONCLUSTERED INDEX SNONDEPT1 ON STUDENT(SDEPT ASC)/*如果没有特殊说明一般情况下创建的索引默认都为NONCLUSTERED的*/
CREATE NONCLUSTERED INDEX SNONAGE ON STUDENT (SAGE ASC,SBIRTH ASC)/*创建多字段非聚簇索引*/
/*删除一个索引格式为:DROP INDEX table_name.index_name*/
DROP INDEX STUDENT.SNONDEPT1
/*以下这两条可以查看sql语句的执行效率,在执行sql语句的以前先执行一下该语句,在执行了sql语句后在消息中即可看到详细说明*/
set statistics io on
set statistics time on
set showplan_text on

视图

 

set statistics io on
set statistics time on
exec sp_helptext computer--查看已经创建好的视图的sql语句
-------------------------------------------------------------------
CREATE VIEW STU AS SELECT SNO,SNAME,SGENTLE,SDEPT FROM STUDENT

SELECT * FROM STU
---------------------------------------------------------------------------
CREATE VIEW STUMAIL AS SELECT SNO,SNAME,SGENTLE,SDEPT FROM STUDENT WHERE SGENTLE='男'

SELECT * FROM STUMAIL
--------------------------------------------------------------------------
CREATE VIEW COMPUTER(SNO,SNAME,CNO,GRADE)
AS
SELECT STUDENT.SNO,STUDENT.SNAME,SC.CNO,SC.GRADE
FROM STUDENT JOIN SC
ON STUDENT.SNO = SC.SNO
WHERE STUDENT.SDEPT='计算机'

select *from computer
----------------------------------------------------------------------------
SELECT STUDENT.SNO,STUDENT.SNAME,SC.CNO,SC.GRADE
FROM STUDENT,SC
WHERE STUDENT.SNO = SC.SNO and STUDENT.SDEPT='计算机'

SELECT STUDENT.SNO,STUDENT.SNAME,SC.CNO,SC.GRADE
FROM STUDENT JOIN SC
ON STUDENT.SNO = SC.SNO
WHERE STUDENT.SDEPT='计算机'
--------------------------------------------------------------------------
CREATE VIEW COMDATA
AS
SELECT STUDENT.SNO 学号,STUDENT.SNAME 姓名,STUDENT.SGENTLE 性别,COURSE.CNAME 课程名,COURSE.CGRADE 学分,SC.GRADE 成绩
FROM STUDENT JOIN SC
ON STUDENT.SNO = SC.SNO
JOIN COURSE
ON COURSE.CNO = SC.CNO
WHERE STUDENT.SDEPT='计算机'
AND COURSE.CNAME='数据结构'

SELECT * FROM COMDATA
-----------------------------------------------------------------------------
CREATE VIEW COMDATA1
AS
SELECT 学号,姓名,成绩
FROM COMDATA

SELECT * FROM COMDATA1
-------------------------------------------------------------------------------
CREATE VIEW STU1
(SUM,SDEPT)---不指定具体的列时会报错
AS
SELECT COUNT(*),SDEPT
FROM STUDENT
GROUP BY SDEPT--不加group by 时会报错

SELECT * FROM STU1
----------------------------------------------------------------------------
CREATE VIEW COUR
(SNO1,SNAME,SGENTLE,SAGE,SBIRTH,SDEPT,SNO2,CNO,GRADE)----不指定具体的列时会报错
AS
SELECT STUDENT.*,SC.*
FROM STUDENT JOIN SC
ON STUDENT.SNO = SC.SNO
WHERE SC.GRADE>80

SELECT * FROM COUR