SQL中“ ` ”的作用是什么?
看到别人的代码,
<code>'SELECT '.$param['field'].' FROM `'.DBPRE.$param['table']</code>
from后面的`这个符号有什么作用呢?
回复内容:
看到别人的代码,
<code>'SELECT '.$param['field'].' FROM `'.DBPRE.$param['table']</code>
from后面的`这个符号有什么作用呢?
所有的数据库都有类似的设置,不过mysql用的是`而已。通常用来说明其中的内容是数据库名、表名、字段名。例如
<code>select from from table;</code>
第一个from是字段名,最后的table也是字段名,但是同时也是mysql关键字,这样执行的时候就会报错,所以应该使用
<code>select `from` from `table`</code>
当然,为了便于阅读,不建议使用关键字作为字段名、表名,同时,应该对数据库名、表名、字段名用一对儿反引号包含。
避免和关键字冲突,就是告诉mysql里面的是普通字符串,不是啥命令
避免和 mysql 的本身的关键字 冲突 所以 用这个符号括起来 虽然有时候不影响 查询 但是最好是要 加上的

Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics

In this chapter, we will understand the Environment Variables, General Configuration, Database Configuration and Email Configuration in CakePHP.

PHP 8.4 brings several new features, security improvements, and performance improvements with healthy amounts of feature deprecations and removals. This guide explains how to install PHP 8.4 or upgrade to PHP 8.4 on Ubuntu, Debian, or their derivati

To work with date and time in cakephp4, we are going to make use of the available FrozenTime class.

To work on file upload we are going to use the form helper. Here, is an example for file upload.

In this chapter, we are going to learn the following topics related to routing ?

CakePHP is an open-source framework for PHP. It is intended to make developing, deploying and maintaining applications much easier. CakePHP is based on a MVC-like architecture that is both powerful and easy to grasp. Models, Views, and Controllers gu

Visual Studio Code, also known as VS Code, is a free source code editor — or integrated development environment (IDE) — available for all major operating systems. With a large collection of extensions for many programming languages, VS Code can be c

Validator can be created by adding the following two lines in the controller.
