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                # 第十節:ORM作業 # ORM作業: 假設有以下`ORM`模型: ``` <pre class="calibre12">``` <span class="hljs-keyword">from</span> django.db <span class="hljs-keyword">import</span> models <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">Student</span><span class="hljs-params">(models.Model)</span>:</span> <span class="hljs-string">"""學生表"""</span> name = models.CharField(max_length=<span class="hljs-params">100</span>) gender = models.SmallIntegerField() <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">Meta</span>:</span> db_table = <span class="hljs-string">'student'</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">Course</span><span class="hljs-params">(models.Model)</span>:</span> <span class="hljs-string">"""課程表"""</span> name = models.CharField(max_length=<span class="hljs-params">100</span>) teacher = models.ForeignKey(<span class="hljs-string">"Teacher"</span>,on_delete=models.SET_NULL,null=<span class="hljs-keyword">True</span>) <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">Meta</span>:</span> db_table = <span class="hljs-string">'course'</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">Score</span><span class="hljs-params">(models.Model)</span>:</span> <span class="hljs-string">"""分數表"""</span> student = models.ForeignKey(<span class="hljs-string">"Student"</span>,on_delete=models.CASCADE) course = models.ForeignKey(<span class="hljs-string">"Course"</span>,on_delete=models.CASCADE) number = models.FloatField() <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">Meta</span>:</span> db_table = <span class="hljs-string">'score'</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">Teacher</span><span class="hljs-params">(models.Model)</span>:</span> <span class="hljs-string">"""老師表"""</span> name = models.CharField(max_length=<span class="hljs-params">100</span>) <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">Meta</span>:</span> db_table = <span class="hljs-string">'teacher'</span> ``` ``` 使用之前學到過的操作實現下面的查詢操作: 1. 查詢平均成績大于60分的同學的id和平均成績; 2. 查詢所有同學的id、姓名、選課的數量、總成績; 3. 查詢姓“李”的老師的個數; 4. 查詢沒學過“李老師”課的同學的id、姓名; 5. 查詢學過課程id為1和2的所有同學的id、姓名; 6. 查詢學過“黃老師”所教的“所有課”的同學的id、姓名; 7. 查詢所有課程成績小于60分的同學的id和姓名; 8. 查詢沒有學全所有課的同學的id、姓名; 9. 查詢所有學生的姓名、平均分,并且按照平均分從高到低排序; 10. 查詢各科成績的最高和最低分,以如下形式顯示:課程ID,課程名稱,最高分,最低分; 11. 查詢沒門課程的平均成績,按照平均成績進行排序; 12. 統計總共有多少女生,多少男生; 13. 將“黃老師”的每一門課程都在原來的基礎之上加5分; 14. 查詢兩門以上不及格的同學的id、姓名、以及不及格課程數; 15. 查詢每門課的選課人數;
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