mysql - Update value in one table with result from another

Question

OK I have 2 tables:

holdings: (id, long_name, value, date, sedol)
asset_key: (id, long_name, sedol)

My issue is that in holdings there are many records where the sedol wasn't filled in. I have the asset_key table however that maps a given long_name to a sedol.

Is there a query that can populate holdings.sedol with the result from asset_key?

Something like:

UPDATE holdings SET holdings.sedol = 
    SELECT asset_key.sedol FROM asset_key 
    WHERE sedol.long_name = asset_key.long_name

Answer 1

这可以解决问题：

UPDATE 
  holdings 
    LEFT JOIN asset_key ON sedol.long_name = asset_key.long_name 
SET 
  holdings.sedol=asset_key.sedol

Answer 2

这应该有效：

UPDATE `holdings`
SET `holdings`.`sedol` = (SELECT `asset_key`.`sedol`
                          FROM   `asset_key`
                          WHERE  `asset_key`.`long_name` = `holdings`.`long_name`)

但是，如果我没记错的话，你应该确保这个SELECT子查询只返回一行，否则 MySQL 会抛出错误。

Answer 3

试试下面的查询：

update holdings 
SET holdings.sedol = asset_key.sedol
from holdings
inner join  asset_key on sedol.long_name = asset_key.long_name

注意：内部连接应该只产生单个值