單項選擇題查詢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


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2.單項選擇題一個電視經(jīng)銷商在表Tvtype中維護庫存的電視信息,下述()語句能顯示價格(iprice)最昂貴的三種電視機的信息(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