單項(xiàng)選擇題為數(shù)據(jù)庫表創(chuàng)建索引的目的是()

A.提高查詢的檢索性能
B.創(chuàng)建唯一索引
C.與SQLServer數(shù)據(jù)檢索的速度無關(guān)
D.加快數(shù)據(jù)庫打開的速度


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1.單項(xiàng)選擇題有關(guān)SQLSERVER 2008創(chuàng)建數(shù)據(jù)表的說法,以下正確的是()

A.數(shù)據(jù)庫對(duì)創(chuàng)建表的數(shù)量沒有限制
B.創(chuàng)建數(shù)據(jù)庫表示不能同時(shí)創(chuàng)建約束
C.創(chuàng)建數(shù)據(jù)庫表的同時(shí)創(chuàng)建主鍵,實(shí)際上是在創(chuàng)建表后對(duì)表進(jìn)行修改
D.創(chuàng)建數(shù)據(jù)庫表的同時(shí)創(chuàng)建外鍵,實(shí)際上是在創(chuàng)建表后對(duì)表進(jìn)行修改

3.單項(xiàng)選擇題查詢student表中的所有非空email信息,以下語句正確的是()

A.Select email from student where email!=null
B.Select email from student where emailnotisnull
C.Select email from student where email<>null
D.Select email from student where emailisnotnull

5.單項(xiàng)選擇題一個(gè)電視經(jīng)銷商在表Tvtype中維護(hù)庫存的電視信息,下述()語句能顯示價(jià)格(iprice)最昂貴的三種電視機(jī)的信息(cDiscription)

A.select top3 cDiscription fromTvtype order by iprice asc
B.select cDiscription from Tvtype where max(iprice)>3
C.select top3 cDiscription from Tvtype order by iprice desc
D.selec tcDiscription max(iprice)from Tvtype order by iprice