题目内容

下列关于DEFAULT约束的说法，正确的是 ( )

A. 一个DEFAULT约束可用于一个表的多个列上
B. DEFAULT约束只能作为表级完整性约束
C. DEFAULT约束只能作为列级完整性约束
DEFAULT约束既可作为表级完整性约束也可作为列级完整性约束

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下列删除计算机系学生的修课记录的语句，正确的是 ( )

A. DELETE FROM SC JOIN Student b ON S.Sno = b.SnoWHERE Sdept = '计算机系'
B. DELETE FROM SC FROM SC JOIN Student b ON SC.Sno = b.SnoWHERE Sdept = '计算机系'
C. DELETE FROM Student WHERE Sdept = '计算机系'
DELETE FROM SC WHERE Sdept = '计算机系'

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