Question

我的数据库students中有两个表：

GRADE_REPORT：

+----------------+-------------+------+
|StudentNo       | SectionId   | Grade| 
+----------------+-------------+------+
| 11             | 85          | B    |     
| 17             | 112         | B    |
| 17             | 119         | C    |     
| 17             | 135         | A    |
| 8              | 85)         | A    |     
| 8              | 92          | A    |
+----------------+-------------+------+

STUDENT：

+----------------+-------------+------+--------+----------------+
| StudentNumber  | name        | Classification| DepartmentName |
+----------------+-------------+---------------+----------------+
| 17             | Bill Smith  | 1             |      CS        |       
| 8              | Bob Brown   | 2             |      CS        |
| 11             | Nick Fiener | 4             |      MATH      |       
+----------------+-------------+------+-----+---------+---------+

我试图找到所有做在任何课程中没有A级的学生的学号，姓名和主要部门。所以当我运行查询时，我期待以下内容：

+----------------+-------------+----------------+
| StudentNumber  | name        | DepartmentName |
+----------------+-------------+----------------+
| 11             | Nick Fiener | MATH           |

这是我到目前为止的陈述：

SELECT students.STUDENT.StudentNumber, students.STUDENT.name,
  students.STUDENT.DepartmentName 
FROM students.GRADE_REPORT
INNER JOIN students.STUDENT 
ON students.GRADE_REPORT.StudentNo = students.STUDENT.StudentNumber
WHERE 
( (students.GRADE_REPORT.Grade = "B"  
   OR 
   students.GRADE_REPORT.Grade = "C" ) 
   AND  students.GRADE_REPORT.Grade != "A")  
GROUP BY students.GRADE_REPORT.StudentNo;

编辑：

SELECT students.STUDENT.StudentNumber, students.STUDENT.name, students.STUDENT.DepartmentName 
    FROM students.STUDENT S
        WHERE NOT EXISTS(SELECT students.GRADE_REPORT.StudentNo
                                                    FROM students.GRADE_REPORT gr
                                                        WHERE gr.StudentNo = S.StudentNumber
                                                            AND gr.Grade = "A");

Answer 1

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not exists

仅当特定列的值不存在时才获取行值

1 个答案: