mysql - 如何通过下图更新表格？

Question

我想像这样更新我的表

关系 A.id = B.a_id

Answer 1

对于 MySQL:

UPDATE B
JOIN A ON B.email = A.email
AND B.a_id = A.id
SET B.email = '';

UPDATE B
JOIN (
    SELECT * 
    FROM B
    GROUP BY email, a_id
    HAVING COUNT(*) > 1
) AS dp ON B.email = dp.email
AND B.a_id = dp.a_id
AND B.id != dp.id
SET B.email = '';