数据库中查询grade不及格学生的学号，姓名，选修课程号，选修课程名称，选修课程学分以及成绩

查询未达到及格标准的学生信息，通常需要通过数据库操作来获取。假设我们有一个学生表(students)记录了学号(student_id)，姓名(name)，选修课程(course选修表(course_enrollments)关联了学号、课程号(course_id)、课程名称(course_name)、课程学分(course_credit)以及成绩(grade)。 SQL查询语句可能会类似这样： ```sql SELECT s.student_id AS 学号, s.name AS 姓名, ce.course_id AS 选修课程号, c.course_name AS 选修课程名称, ce.credit AS 选修课程学分, ce.grade AS 成绩 FROM students s JOIN course_enrollments ce ON s.student_id = ce.student_id JOIN courses c ON ce.course_id = c.course_id WHERE ce.grade < '及格分数线'; -- 例如60分 ``` 这里假设grade字段是以百分制表示，并且有明确的不及格分数线。实际查询时，你需要替换'及格分数线'为你系统的具体标准。

很抱歉，作为语言模型，我不能直接连接数据库进行数据检索。但是，我可以提供一些 SQL 查询语句的示例，您可以根据这些示例进行相应的查询操作： 1. 检索“程军”老师所授课程的课程号和课程名： ``` SELECT Cno, Cname FROM Course WHERE Cpno IN (SELECT Cno FROM Course WHERE Cname = '程军'); ``` 2. 检索年龄大于19岁男学生的学号和姓名： ``` SELECT Sno, Sname FROM Student WHERE Ssex = '男' AND Sage > 19; ``` 3. 检索“李勇”同学不学课程的课程号： ``` SELECT Cno FROM Course WHERE Cno NOT IN (SELECT Cno FROM SC WHERE Sno = (SELECT Sno FROM Student WHERE Sname = '李勇')); ``` 4. 检索至少选修两门课程的学生学号： ``` SELECT Sno FROM SC GROUP BY Sno HAVING COUNT(*) >= 2; ``` 5. 检索选修课程号为1和2的学生学号： ``` SELECT Sno FROM SC WHERE Cno IN ('1', '2'); ``` 6. 检索至少选修“程军”老师所授全部课程的学生姓名： ``` SELECT Sname FROM Student WHERE Sno IN (SELECT Sno FROM SC WHERE Cno IN (SELECT Cno FROM Course WHERE Cpno IN (SELECT Cno FROM Course WHERE Cname = '程军')) GROUP BY Sno HAVING COUNT(*) = (SELECT COUNT(*) FROM Course WHERE Cpno IN (SELECT Cno FROM Course WHERE Cname = '程军'))); ``` 7. 检索选修课程包含学号为201215122的学生所修课程的学生学号： ``` SELECT DISTINCT Sno FROM SC WHERE Cno IN (SELECT Cno FROM SC WHERE Sno = '201215122'); ``` 8. 检索全部学生都选修的课程的课程号和课程名： ``` SELECT Cno, Cname FROM Course WHERE Cno IN (SELECT Cno FROM SC GROUP BY Cno HAVING COUNT(*) = (SELECT COUNT(*) FROM Student)); ``` 9. 检索选修全部课程的学生姓名： ``` SELECT Sname FROM Student WHERE Sno IN (SELECT Sno FROM SC GROUP BY Sno HAVING COUNT(*) = (SELECT COUNT(*) FROM Course)); ``` 10. 查询所在系是CS系的学生选修的课程的课程名和学分，结果按课程名降序排序： ``` SELECT C.Cname, C.Ccreadit FROM SC AS S JOIN Course AS C ON S.Cno = C.Cno JOIN Student AS St ON S.Sno = St.Sno WHERE St.Sdept = 'CS' ORDER BY C.Cname DESC; ``` 11. 检索“数据库”课程成绩高于90分的所有学生的学号、姓名和分数： ``` SELECT S.Sno, S.Sname, SC.Grade FROM Student AS S JOIN SC ON S.Sno = SC.Sno JOIN Course AS C ON SC.Cno = C.Cno WHERE C.Cname = '数据库' AND SC.Grade > 90; ``` 12. 查询男生和女生选修课程的平均成绩： ``` SELECT S.Ssex, AVG(SC.Grade) AS AvgGrade FROM Student AS S JOIN SC ON S.Sno = SC.Sno GROUP BY S.Ssex; ``` 13. 检索没有选课的学生的学号和姓名： ``` SELECT S.Sno, S.Sname FROM Student AS S WHERE S.Sno NOT IN (SELECT Sno FROM SC); ``` 14. 检索没有任何一门课程成绩不及格的学生的信息，包括学号、姓名： ``` SELECT S.Sno, S.Sname FROM Student AS S WHERE S.Sno NOT IN (SELECT Sno FROM SC WHERE Grade < 60); ```