Detailed explanation of adding, deleting, checking and modifying database in PHP (with pictures)

The steps to implement addition, deletion, and modification in php are as follows:

1. Establish a connection to the database

php itself provides support for mysql database. Use the mysql_connect function to connect. The syntax is as follows:

resource mysql_connect([string server [, string username [,string password [, bool new_link [, int_client_flags]]]]])

This function is used to open or reuse a connection to the mysql server. Server is the MySQL server that needs to be connected. It can include the port number separated by English colons, such as "hostname:port". username and password are respectively the username and password required when connecting to data. The new_link parameter defaults to FALSE. If mysql_connect() is called a second time with the same parameters, a new connection will not be established, but the already opened connection ID will be returned. When set to false, new connections are always opened.

<p>连接到mysql数据库</p>
<?php
header("Content-Type: text/html;charset=utf-8");
error_reporting(0); //禁止错误输出
$link = mysqli_connect(&#39;127.0.0.1:3306&#39;,&#39;root&#39;,&#39;root&#39;); //创建数据库连接
if(!$link){ //如果失败
    die(&#39;连接mysql数据库失败&#39;.mysqli_error()); //显示出错误信息
}
echo &#39;连接mysql服务器成功!&#39;; //否则显示连接成功的信息
mysqli_close($link); //最后关闭数据库连接

2. Create database and data table

<p>创建mydbdemo数据库</p>
<?php
header("Content-Type: text/html;charset=utf-8");
error_reporting(0); //禁止错误输出
$con = mysqli_connect(&#39;127.0.0.1:3306&#39;,&#39;root&#39;,&#39;root&#39;); //创建数据库连接
if(!$con){ //如果失败
    die(&#39;连接mysql数据库失败&#39;.mysqli_error()); //显示出错误信息
}
 
if(mysqli_query("create database mydbdemo",$con)){ //创建数据库
	echo "创建数据库 mydbdemo 成功"; //成功后的提示
}else{ //如果失败
    echo "创建数据库失败".mysqli_error(); //出错提示
}
mysqli_close($con); //关闭数据库连接
?>

<p>创建 fruit 数据表</p>
<?php
header("Content-Type: text/html;charset=utf-8");
error_reporting(0); //禁止错误输出
$con = mysqli_connect(&#39;127.0.0.1:3306&#39;,&#39;root&#39;,&#39;root&#39;); //创建数据库连接
if(!$con){ //如果失败
    die(&#39;连接mysql数据库失败&#39;.mysqli_error()); //显示出错误信息
}
 
mysqli_select_db("mydbdemo",$con); //选择需要使用的数据库
$sql = "create table fruit
(name varchar(15),
 color varchar(15),
 price float
)"; //使用mysqli_query执行sql语句
mysqli_query($sql,$con);
echo "<p>创建数据表 fruit 成功</p>";
mysqli_close($con);
?>

3. Add, delete, check and modify sql statements

insert into fruit (name,color,price) values ('苹果','绿色','八块五');
update fruit set price='9.9' where price = '8.8';
select * from fruit;
delete from fruit where price = '8.8' ;

4. mysqli_query() executes sql statement

mysqli_query($sql);

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