password='password',host='localhost',database='database_name')cursor=cnx.cursor()# 更新单个值update_single_value_query="UPDATE users SET name = 'Tom' WHERE id = 1;"cursor.execute(update_single_value_query)# 更新多个值update_multiple_values_query="UPDATE users SET name = 'Tom', age = ...
MySQL supports one-to-many relationship where one record in a table corresponds to multiple records in another table. In this relationship, we often use foreign keys to represent the link between tables. section Updating the first record To update the first record in a one-to-many relationship,...
您必须将数据作为行集提供,并使用multiple-table更新: UPDATE tJOIN ( SELECT 'A' AS user, 30 AS balance_change UNION ALL SELECT 'B', 60 UNION ALL SELECT 'C', 10 ) AS t1 USING (user)SET t.balance = t.balance - t1.balance_change, t.used = t.used + t1.balance_change WHERE t.bala...
UPDATEmytableSETmyfield ='value'WHEREother_field ='other_value'; 如果更新同一字段为同一个值,mysql也很简单,修改下where即可: 1 UPDATEmytableSETmyfield ='value'WHEREother_fieldin('other_values'); 这里注意 ‘other_values’ 是一个逗号(,)分隔的字符串,如:1,2,3 那如果更新多条数据为不同的值,...
Re: Update multiple columns with single query Rational Rabbit January 22, 2011 05:57PM Re: Update multiple columns with single query Rick James January 22, 2011 11:38PM Sorry, you can't reply to this topic. It has been closed.
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In MySQL, you can change the data of multiple tables using a single UPDATE statement. If the UPDATE statement violates any integrity constraint, MySQL does not perform the update and issues an error message. The SET clause determines the column names of the table and the new values. The new...
MySQL thread id 239358, OS thread handle 140057371186944, query id 82403598 127.0.0.1 root update insert into dl(num,val) values(101,'sess1') *** (2) HOLDS THE LOCK(S): RECORD LOCKS space id 28 page no 4 n bits 80 index num_index of table `test`.`dl` trx id 47631326 lock_mode...
update usersetage=10where id=49;update usersetage=10where name='Tom'; 第一条SQL使用主键查询,只需要在 id = 49 这个主键索引上加上锁。第二条 SQL 使用二级索引来查询,那么首先在 name = Tom 这个索引上加写锁,然后由于使用 InnoDB 二级索引还需再次根据主键索引查询,所以还需要在 id = 49 这个主键...
My problem is that I might find that most of the records need updating, and this might lead to 100,00+ update statements I cannot use LOAD DATA as this is product database Is there a way to update multiple rows (each with a different value and condition in a single query?