如何使用WHERE子句在MySql中使用select语句更新字段？

Question

我正在尝试从select语句更新字段。这是我当前的查询

UPDATE phone_cals
SET call_code_id = id, result_code_id = 0, call_subject = title WHERE status = 1
select call_code_id AS id, call_code_title AS title FROM call_codes

我正在尝试设置

phone_calls.call_code_id = call_codes.call_code_id 
phone_calls.result_code_id = 0
phone_calls.call_subject = call_codes.call_code_title 

WHERE phone_calls.status = 1

是的我有语法错误，但我不确定如何解决它

总结我想选择一个随机的call_codes.call_code_id并将它分配给phone_calls.call_code_id

Answer 1

如果我理解你的问题，我认为你需要这样的事情：

UPDATE
  phone_calls,
  (select call_code_id, call_code_title FROM call_codes ORDER BY rand() LIMIT 1) c2
SET
  phone_calls.call_code_id = c2.call_code_id,
  phone_calls.result_code_id = 0,
  phone_calls.call_subject = c2.call_code_title
WHERE
  phone_calls.call_subject = 1

这会将所有call_code_id和所有call_subject更新为从call_codes表中选择的随机值，其中call_subject = 1。

修改

如果你需要将每一行更新为不同的随机值，我认为你可以使用它：

UPDATE
  phone_calls
SET
  call_code_id = (select call_code_id FROM call_codes ORDER BY rand() LIMIT 1),
  result_code_id = 0
WHERE
  phone_calls.call_subject = 1;

UPDATE
  phone_calls INNER JOIN call_codes
  ON phone_calls.call_code_id = call_codes.call_code_id
SET
  phone_calls.call_subject = call_codes.call_code_title
WHERE
  phone_calls.call_subject = 1;

（不知道是否可以只使用一个查询来完成它）。它可能很慢，但应该有效。