A.禁止删除
B.同时删除所有参照记录
C.将参照记录的外部关键字值置为空值
D.将参照记录的外部关键字值置为默认值
第1题
A. 删除子表的记录,主表相关记录一同删除
B. 删除主表的记录,子表相关记录一同删除
C. 子表相关记录存在,不能删除主表记录
D. 主表相关记录存在,不能删除子表记录
第2题
A.ON DELETE CASCADES
B.ON DEL ETE RESTRICTED
C.ON UPDATE CASCADES
D.ON UPDATE RESTRICTED
第3题
A.ON DELETE CASCADES
B.ON DELETE RESTRICTED
C.ON DELETE NULLIFIES
D.ON DELETE DEFAULT
第4题
A.ONDELETE CASCADES
B.ONDELETE RESTRICTED
C.ONDELETE NULLIFIES
D.ONDELETE DEFAULT
第5题
A.ONDELETE CASCADES
B.ONDELETE RESTRICTED
C.ONDELETE NULLIFIES
D.ONDELETE DEFAULT
第6题
A ) ON DELETE CASCADES
B ) ON DELETE RESTRICTED
C ) ON UPDATE CASCADES
D ) ON UPDATE RESTRICTED
第7题
A.WHEN DELETE RESTRICT
B.ON DELETE RESTRICT
C.ON DELETE SET NULL
D.ON DELETE CASCADE
第8题
A.WHEN DELETE RESTRICT
B.ON DELETE RESTRICT
C.ON DELETE SET NULL
D.ON DELETE CASCADE
第9题
A.外部键约束能防止删除行如果删除行违反外部键中定义的关系的话
B.外部键约束确保在删除行之前对数据表有正确的权限
C.如果只有一行的被删除,该外部键约束将被忽略
D.外部键对删除表述没有影响
第10题
A.ON DELETE CASCADES
B.ON DELETE RESTRICTED
C.ON DELETE NULLIFIES
D.ON DELETE DEFAULT
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