MySQL MySQL更新列+1？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/3866524/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
MySQL Update Column +1?
提问by Cory
I was wondering what would be the easiest way to update a column by +1? I will be updating a post count of a category based on when users submits a new post.
我想知道通过 +1 更新列的最简单方法是什么？我将根据用户提交新帖子的时间更新类别的帖子数。
Thanks.
谢谢。
回答by OMG Ponies
The easiest way is to notstore the count, relying on the COUNT aggregate function to reflect the value as it is in the database:
最简单的方法是不存储计数，依靠 COUNT 聚合函数来反映数据库中的值：
SELECT c.category_name,
COUNT(p.post_id) AS num_posts
FROM CATEGORY c
LEFT JOIN POSTS p ON p.category_id = c.category_id
You can create a viewto house the query mentioned above, so you can query the view just like you would a table...
您可以创建一个视图来容纳上面提到的查询，这样您就可以像查询表一样查询视图...
But if you're set on storing the number, use:
但是，如果您要存储号码，请使用：
UPDATE CATEGORY
SET count = count + 1
WHERE category_id = ?
..replacing "?" with the appropriate value.
..替换“？” 具有适当的值。
回答by Michael Banzon
You can do:
你可以做：
UPDATE categoriesSET posts= posts+ 1 WHERE category_id= 42;
UPDATE categoriesSET posts= posts+ 1 WHERE category_id= 42;
回答by Vincent Ramdhanie
How about:
怎么样：
update table
set columnname = columnname + 1
where id = <some id>
回答by KoolKabin
update post set count = count + 1 where id = 101
回答by praveenraj4ever
update TABLENAME
set COLUMNNAME = COLUMNNAME + 1
where id = 'YOURID'
回答by Ahamadullah Saikat
update table_name set field1 = field1 + 1;
