[英]Update columns to min value from a group
我有这样的数据库
uniqueid | name | newid | sirname
----------+-------------+-------+---------
A1 | Adam | NULL | Danny
A2 | Adam (Lee) | NULL | Danny
A5 | Adam (Koh) | NULL | Danny
B4 | Bruce | NULL | CK
B6 | Bruce (Lee)| NULL | CK
我如何将所有的newid
从group by sirname
更新为min(unique id)
我想要的结果:
uniqueid | name | newid | sirname
----------+-------------+-------+---------
A1 | Adam | A1 | Danny
A2 | Adam (Lee) | A1 | Danny
A5 | Adam (Koh) | A1 | Danny
B4 | Bruce | B4 | CK
B6 | Bruce (Lee) | B4 | CK
尝试这个:
UPDATE table a
SET new_id = (SELECT MIN(unique_id)
FROM table b
WHERE b.sirname = a.sirname)
试试这个UPDATE JOIN
UPDATE
(
SELECT sirname,MIN(uniqueid) min_uniqueid
FROM mytable GROUP BY sirname
) A
INNER JOIN mytable B
USING (sirname)
SET
B.newid = A.min_uniqueid
;
为了使该查询非常快速地工作,请确保您在sirname和uniqueid上具有复合索引。
如果没有这样的索引,请事先运行:
ALTER TABLE mytable ADD INDEX sirname_uniqueid_ndx (sirname,uniqueid);
试试看 !!!
如果BD。无法使用,请尝试:
Update tableName As a
Set newid =
(Select uniqueid
From tableName As b
Where b.sirname = a.sirname
Order By uniqueid
Limit 1)
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