SQLite问题：查询错误：靠近FROM：语法错误无法执行语句

Question

我一直在SQLite中收到此错误：

  

查询错误：靠近“FROM”：语法错误无法执行语句

SELECT Name, CourseId
    FROM Lecturer JOIN Lecture ON Lecturer.LecturerId = Lecture.LecturerId
    JOIN     (SELECT CourseId   
        FROM Course
        WHERE EXISTS (SELECT * 
                    FROM Exam
                WHERE Exam.CourseId = Course.CourseId
                AND (SELECT COUNT *
                          FROM Exam
                          WHERE Grade > 6)
                <
                (SELECT COUNT *
                FROM Exam
                WHERE Grade < 6)))
    USING Course.Id     

Answer 1

COUNT是一个函数，您需要围绕*

的parens

如：

COUNT(*)

Answer 2

我通常会为内联视图指定一个别名，例如FOO，并使用on ...子句将外部表连接到内联视图：

  select * from x
  join
  (
      select someColumn, someOtherColumn...

  ) as FOO
  on x.somecolumn = FOO.somecolumn

我会这样做：

  select lecture.*, FOO.courseid
  from lecture
  join lecturer on lecture.lecturerid = lecturer.lecturerid
  join
  (
       you inline view selecting the courses

  ) as FOO
  on lecture.courseid = FOO.courseid