Home Backend Development PHP Tutorial mysql的float类型很奇怪的,该如何解决

mysql的float类型很奇怪的,该如何解决

Jun 13, 2016 am 11:58 AM
decimal float mysql nbsp

mysql的float类型很奇怪的
我有个表 test,里面有三个字段,
uid,one,two,uid是int类型,自增,one字段是float(3,2) two字段是float(5,2).

按照道理one字段我可以插入  123.12  这样的数字对吧,也就是前面三位,后面两位
two字段我可以插入前面5位,后面两位吧,但是我插入一条

insert into test values(null,123.12,12345.12) 插入成功了,但是显示的数据则不一样,这是为什么呢


如果我需要插入数值  98.12,即前面2位,小数点两位,这个字段是应该设置成float类型吗
------解决方案--------------------
1、你定义错了
MySQL允许使用非标准语法:FLOAT(M,D)或REAL(M,D)或DOUBLE PRECISION(M,D)。这里,“(M,D)”表示该值一共显示M位整数,其中D位位于小数点后面。例如,定义为FLOAT(7,4)的一个列可以显示为-999.9999。MySQL保存值时进行四舍五入,因此如果在FLOAT(7,4)列内插入999.00009,近似结果是999.0001。

2、有精度要求应使用
DECIMAL和NUMERIC类型在MySQL中视为相同的类型。它们用于保存必须为确切精度的值,例如货币数据。当声明该类型的列时,可以(并且通常要)指定精度和标度;例如:
salary DECIMAL(5,2)
在该例子中,5是精度,2是标度。精度表示保存值的主要位数,标度表示小数点后面可以保存的位数。


------解决方案--------------------
要限制正数应该设置UNSIGNED属性。
------解决方案--------------------
建议用decimal字段表示

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

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

How to open phpmyadmin How to open phpmyadmin Apr 10, 2025 pm 10:51 PM

You can open phpMyAdmin through the following steps: 1. Log in to the website control panel; 2. Find and click the phpMyAdmin icon; 3. Enter MySQL credentials; 4. Click "Login".

MySQL: An Introduction to the World's Most Popular Database MySQL: An Introduction to the World's Most Popular Database Apr 12, 2025 am 12:18 AM

MySQL is an open source relational database management system, mainly used to store and retrieve data quickly and reliably. Its working principle includes client requests, query resolution, execution of queries and return results. Examples of usage include creating tables, inserting and querying data, and advanced features such as JOIN operations. Common errors involve SQL syntax, data types, and permissions, and optimization suggestions include the use of indexes, optimized queries, and partitioning of tables.

MySQL's Place: Databases and Programming MySQL's Place: Databases and Programming Apr 13, 2025 am 12:18 AM

MySQL's position in databases and programming is very important. It is an open source relational database management system that is widely used in various application scenarios. 1) MySQL provides efficient data storage, organization and retrieval functions, supporting Web, mobile and enterprise-level systems. 2) It uses a client-server architecture, supports multiple storage engines and index optimization. 3) Basic usages include creating tables and inserting data, and advanced usages involve multi-table JOINs and complex queries. 4) Frequently asked questions such as SQL syntax errors and performance issues can be debugged through the EXPLAIN command and slow query log. 5) Performance optimization methods include rational use of indexes, optimized query and use of caches. Best practices include using transactions and PreparedStatemen

Why Use MySQL? Benefits and Advantages Why Use MySQL? Benefits and Advantages Apr 12, 2025 am 12:17 AM

MySQL is chosen for its performance, reliability, ease of use, and community support. 1.MySQL provides efficient data storage and retrieval functions, supporting multiple data types and advanced query operations. 2. Adopt client-server architecture and multiple storage engines to support transaction and query optimization. 3. Easy to use, supports a variety of operating systems and programming languages. 4. Have strong community support and provide rich resources and solutions.

How to connect to the database of apache How to connect to the database of apache Apr 13, 2025 pm 01:03 PM

Apache connects to a database requires the following steps: Install the database driver. Configure the web.xml file to create a connection pool. Create a JDBC data source and specify the connection settings. Use the JDBC API to access the database from Java code, including getting connections, creating statements, binding parameters, executing queries or updates, and processing results.

How to start mysql by docker How to start mysql by docker Apr 15, 2025 pm 12:09 PM

The process of starting MySQL in Docker consists of the following steps: Pull the MySQL image to create and start the container, set the root user password, and map the port verification connection Create the database and the user grants all permissions to the database

MySQL's Role: Databases in Web Applications MySQL's Role: Databases in Web Applications Apr 17, 2025 am 12:23 AM

The main role of MySQL in web applications is to store and manage data. 1.MySQL efficiently processes user information, product catalogs, transaction records and other data. 2. Through SQL query, developers can extract information from the database to generate dynamic content. 3.MySQL works based on the client-server model to ensure acceptable query speed.

Centos install mysql Centos install mysql Apr 14, 2025 pm 08:09 PM

Installing MySQL on CentOS involves the following steps: Adding the appropriate MySQL yum source. Execute the yum install mysql-server command to install the MySQL server. Use the mysql_secure_installation command to make security settings, such as setting the root user password. Customize the MySQL configuration file as needed. Tune MySQL parameters and optimize databases for performance.

See all articles