Question

如何在Laravel ORM中做到这一点？

SELECT
    s.id,
    s.name AS NAME,
    COALESCE(su.cnt, 0) AS SUBJECTs,
    COALESCE(e.marks, 0) AS MARKS
FROM student s
LEFT JOIN
(
    SELECT student_id, COUNT(*) AS cnt
    FROM subject
    GROUP BY student_id
) su
    ON s.id = su.student_id
LEFT JOIN
(
    SELECT student_id, SUM(mark) AS marks
    FROM exam
    GROUP BY student_id
) e
    ON s.id = e.student_id;

我想加入学生和主题，学生和考试之间。当我加入第三个表时，就出现了问题，它复制了结果。

Answer 1

这是

DB::table('student as su')->selectRaw("
  su.id,
  su.name,
  COALESCE(su.cnt, 0) as SUBJECTS,
  COALESCE(e.marks, 0) as MARKS
")->leftJoin(DB::raw("(
  SELECT student_id, COUNT(*) AS cnt
  FROM subject
  GROUP BY student_id
) su"), 's.id', '=', 'su.student_id')
->leftJoin(DB::raw("(
  SELECT student_id, SUM(mark) AS marks
  FROM exam
  GROUP BY student_id
) e"), 's.id', '=', 'e.student_id')

将此SQL语句转换为Laravel ORM

1 个答案: