單個查詢更新並在mysql中選擇內連接

Question

如何結合這兩個查詢？

選擇mysql查詢：

SELECT avg(b.averageRating) 
FROM review a INNER 
JOIN review b ON b.institudeId=a.institudeId 
WHERE a.reviewId='3';

更新mysql查詢：

update table institutions 
set averageRatings=avg(b.averageRating) 
where id=a.institudeId;

Answer 1

您可以嘗試以下查詢：

UPDATE institutions SET institutions.overallRatings = (
  SELECT avg(b.averageRating) 
  FROM review a 
  INNER JOIN review b ON b.institudeId=a.institudeId WHERE a.reviewId='3'
) 
WHERE institutions.id = (
  SELECT institudeId FROM review WHERE reviewId='3'
)