如何使用WHERE子句在MySql中更新选择语句的字段？

Question

我正在尝试从select语句更新字段。 这是我目前的查询

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

我正在尝试设定

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，但不确定如何解决

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

Answer 1

如果我正确理解了您的问题，我认为您需要以下内容：

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。

编辑

如果您需要将每一行更新为不同的随机值，我认为您可以使用以下方法：

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;

（不知道是否可以仅使用一个查询来完成此操作）。 它可能很慢，但应该可以。