Community Learn Tools Library Leisure
search
English
Home > Database > Mysql Tutorial > MySQL分组数据_MySQL

MySQL分组数据_MySQL

WBOY
Release： 2016-06-01 13:06:44
Original
1120 people have browsed it

分组

理解分组可以看如下一个例子，首先我们打印出products表如下

从上面的表中可以看出，每个vendor都有若干个产品，那么怎么一次统计每个vendor有多少个产品呢？ 这里就可以使用GROUP BY，如下

如果不使用group by，那么结果就是统计有多少行了：

分组过滤

分组过滤也就是多统计后的数据再进行过滤，如上面的例子中，统计出来了每一个vendor有多个产品，那么可以使用HAVING来过滤出 产品数量多于3个的vendor:

WHERE 语句可以喝HAVING语句一起灵和使用，如需要找出，有2种以上的产品价格大于10：

source：php.cn
Previous article：Priority queue optimization for filesort is now visible in M_MySQL Next article：[原]mysql学习笔记：存储过程_MySQL
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Latest Articles by Author
Latest Issues
function_exists() cannot determine the custom function Function test () {return true;} if (function_exists ('test')) {echo "test is function...
From 2024-04-29 11:01:01
0
3
2310
How to display the mobile version of Google Chrome Hello teacher, how can I change Google Chrome into a mobile version?
From 2024-04-23 00:22:19
0
11
2445
The child window operates the parent window, but the output does not respond. The first two sentences are executable, but the last sentence cannot be implemented.
From 2024-04-19 15:37:47
0
1
2060
There is no output in the parent window document.onclick = function(){ window.opener.document.write('I am the output of the child ...
From 2024-04-18 23:52:34
0
1
1948
Where is the courseware about CSS mind mapping? Courseware
From 2024-04-16 10:10:18
0
0
2010
Related Topics
More>
Popular Recommendations
Popular Tutorials
More>
Related Tutorials
Popular Recommendations
Latest courses
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template