在线名词解释大全 - 数据库系统 - 详细

已知下述关系,S(学号,姓名,年龄,性别,院系),SC(学号,课程号,分数),C(课程号,课程名,学分,教师名)。检索学习过刘玲老师所授课程的所有学生。表达正确的是________

A
https://exam-online.oss-cn-beijing.aliyuncs.com/505a.png/>},{key:B,value:、https://exam-online.oss-cn-beijing.aliyuncs.com/505b.png/>},{key:C,value:、https://exam-online.oss-cn-beijing.aliyuncs.com/505c.png/>},{key:D,value:、https://exam-online.oss-cn-beijing.aliyuncs.com/505d.png/>}]、[{"key":"A","value":" class="import-img" "},{"key":"B","value":" class="import-img" "},{"key":"C","value":" class="import-img" "},{"key":"D","value":" class="import-img" "}]
B
https://exam-online.oss-cn-beijing.aliyuncs.com/505a.png/>},{key:B,value:、https://exam-online.oss-cn-beijing.aliyuncs.com/505b.png/>},{key:C,value:、https://exam-online.oss-cn-beijing.aliyuncs.com/505c.png/>},{key:D,value:、https://exam-online.oss-cn-beijing.aliyuncs.com/505d.png/>}]、[{"key":"A","value":" class="import-img" "},{"key":"B","value":" class="import-img" "},{"key":"C","value":" class="import-img" "},{"key":"D","value":" class="import-img" "}]
C
https://exam-online.oss-cn-beijing.aliyuncs.com/505a.png/>},{key:B,value:、https://exam-online.oss-cn-beijing.aliyuncs.com/505b.png/>},{key:C,value:、https://exam-online.oss-cn-beijing.aliyuncs.com/505c.png/>},{key:D,value:、https://exam-online.oss-cn-beijing.aliyuncs.com/505d.png/>}]、[{"key":"A","value":" class="import-img" "},{"key":"B","value":" class="import-img" "},{"key":"C","value":" class="import-img" "},{"key":"D","value":" class="import-img" "}]
D
https://exam-online.oss-cn-beijing.aliyuncs.com/505a.png/>},{key:B,value:、https://exam-online.oss-cn-beijing.aliyuncs.com/505b.png/>},{key:C,value:、https://exam-online.oss-cn-beijing.aliyuncs.com/505c.png/>},{key:D,value:、https://exam-online.oss-cn-beijing.aliyuncs.com/505d.png/>}]、[{"key":"A","value":" class="import-img" "},{"key":"B","value":" class="import-img" "},{"key":"C","value":" class="import-img" "},{"key":"D","value":" class="import-img" "}]
E
https://exam-online.oss-cn-beijing.aliyuncs.com/505a.png/>},{key:B,value:、https://exam-online.oss-cn-beijing.aliyuncs.com/505b.png/>},{key:C,value:、https://exam-online.oss-cn-beijing.aliyuncs.com/505c.png/>},{key:D,value:、https://exam-online.oss-cn-beijing.aliyuncs.com/505d.png/>}]、[{"key":"A","value":" class="import-img" "},{"key":"B","value":" class="import-img" "},{"key":"C","value":" class="import-img" "},{"key":"D","value":" class="import-img" "}]
F
https://exam-online.oss-cn-beijing.aliyuncs.com/505a.png/>},{key:B,value:、https://exam-online.oss-cn-beijing.aliyuncs.com/505b.png/>},{key:C,value:、https://exam-online.oss-cn-beijing.aliyuncs.com/505c.png/>},{key:D,value:、https://exam-online.oss-cn-beijing.aliyuncs.com/505d.png/>}]、[{"key":"A","value":" class="import-img" "},{"key":"B","value":" class="import-img" "},{"key":"C","value":" class="import-img" "},{"key":"D","value":" class="import-img" "}]
正确答案:
Explanation 选项B缺少连接条件;选项C条件的逻辑连接关系错误;选项D不是对所有教师验证,而只要有一位老师即可。
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