mysql - 按行计数的计数

Question

这里我得到了三行计数的值，但我需要该行计数...

但无法编写查询...请帮助我...

SELECT COUNT(*) 
  FROM sg_examinations e
  JOIN sg_exam_types t
    ON t.id = e.exam_name 
  LEFT 
  JOIN sg_courses c
    ON c.id = e.course_id
 WHERE e.branch_id = 1 
   AND e.academic_year = 2     
 GROUP 
    BY e.exam_name
     , e.course_id

Answer 1

你的意思是:

SELECT e.exam_name, e.course_id, COUNT(*) 
  FROM sg_examinations e
  JOIN sg_exam_types t
    ON t.id = e.exam_name 
  LEFT 
  JOIN sg_courses c
    ON c.id = e.course_id
 WHERE e.branch_id = 1 
   AND e.academic_year = 2     
 GROUP 
    BY e.exam_name, e.course_id