简体中文(ZH-CN) English(EN) 繁体中文(ZH-TW) 日本語(JA) 한국어(KO) Melayu(MS) Français(FR) Deutsch(DE)
Home > Backend Development > PHP Tutorial > body text

mysql创建表时的空值和非空值设置有什么讲究?

PHP中文网
Release： 2016-06-23 14:03:25
Original
1513 people have browsed it

mysql创建表时的空值和非空值设置有什么讲究?


回复讨论(解决方案)

有人回答没？？？？

我一般尽量不用null  
 
如果你的0和null或者''和null有不同含义, 那么就需要允许空置

这要看你的业务需求了  
空 NULL 表示什么都没有输入，也就是该数据项是无效的  
 
如果你的业务需要数据项有初值，那么就应该用 NOT NULL（不为空）并设置初值

以上就是mysql创建表时的空值和非空值设置有什么讲究?的内容，更多相关内容请关注PHP中文网（www.php.cn）！


Related labels：
mysql null value
source：php.cn
Previous article：网址改变，求救RewriteRule 正则表达式 Next article：求教list列表中，相连两行的位置交换的mysql语句？
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
How to display only the lowest value from a result set (MYSQL) I have the following statement: selectDATE(recieved_on)asDay,round(count(*)/24)AS'average'...
From 2024-04-06 21:44:19
0
1
603
Calculate the sum of fields in another table using MySQL SQL query I have a schema like this: User table with attributes "user_id" and "userna...
From 2024-04-06 19:39:29
0
1
441
MySQL: "Select text from... as <variable here or subquery>" I have the following table with the following data: id text language 1 german text german ...
From 2024-04-06 19:25:54
0
2
529
How to group and count in MySQL? I'm trying to write a query that extracts the total number of undeleted messages sent to f...
From 2024-04-06 18:30:17
0
1
353
MySQL gets data from multiple tables I have a eg_design table which contains the following columns: and eg_domains table which ...
From 2024-04-06 18:42:44
0
2
479
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
About us Disclaimer Sitemap
php.cn：Public welfare online PHP training，Help PHP learners grow quickly！