Detailed summary and examples of mysql operations (1)

Foreword: Relational database management systems are absolutely unavoidable in back-end development. Common database management systems include MySQL, SQL Server, Oracle, etc.

Mysql is the most commonly used database management system. Today I will introduce Mysql to you.

Recommend mysql related video tutorials: https://www.php.cn/course/list/51.html

I will summarize and organize relevant knowledge for you in the future. ,Thanks!

Official website download address: https://dev.mysql.com/downloads/mysql/

Note: During the database installation process, we need to enable management You must have user rights to install, otherwise the installation will fail due to insufficient rights.

1. Database initialization, password setting and password modification

Mysql does not have a password by default after the first installation. We can use the following command to set the password. .

mysqladmin -u root password "new_password";

Then connect to the database through the following command:

mysql -u root -p

Enter password:******

Note: The password will not be displayed.

2. Mysql startup and shutdown commands

Start command:

net start mysql

Close command:

net stop mysql

3, mysql connection in PHP

<?php
//配置mysql相关信息
$localhost = &#39;localhost&#39;;
$username = &#39;zmz&#39;;
$password = &#39;20040315&#39;;
$dbname = &#39;zmz&#39;;
$port = 3306;

//连接数据库
$conn = mysqli_connect($localhost,$username,$password,$dbname,$port);
//检查连接
if(!$conn) {
die(&#39;连接数据库失败！&#39;.mysqli_connect_error());
}else {
echo &#39;连接成功！&#39;;
}
//关闭连接
mysqli_close($conn);
?>

4. Database creation

Syntax: create database database name;

Use php script to create a database:

<?php
//配置数据库相关信息
$localhost = &#39;localhost&#39;;
$username = &#39;zmz&#39;;
$password = &#39;20040315&#39;;
$dbname = &#39;zmz&#39;;
$port = 3306;

//连接数据库
$conn = mysqli_connect($localhost,$username,$password,$dbname,$port);
//检查连接
if(mysqli_connect_errno($conn)) {
die(&#39;连接失败！&#39;.mysqli_connect_error());
}else {
echo &#39;连接成功！&#39;;
}
//创建数据库
$sql = "CREATE DATABASE demo03";
$res = mysqli_query($conn,$sql);
if($res){
echo &#39;创建成功！&#39;;
}else {
echo &#39;创建失败！&#39;;
}
//关闭连接
mysqli_close($conn);
?>

5. Delete the database

Syntax:drop database database name;

Use PHP script to delete the database:

<?php
//配置数据库信息
$localhost = &#39;localhost&#39;;
$username = &#39;zmz&#39;;
$password = &#39;20040315&#39;;
$dbname = &#39;zmz&#39;;
$port = 3306;

//连接数据库
$conn = mysqli_connect($localhost,$username,$password,$dbname,$port);
//检查连接
if(mysqli_connect_errno($conn)) {
die(&#39;连接失败！&#39;.mysqli_connect_error());
}
//删除数据库
$sql = "DROP DATABASE demo01";
$query = mysqli_query($conn, $sql);
//var_dump($query);
//die();
//判断是否删除成功
if($query) {
echo &#39;删除成功！&#39;;
}else {
die(&#39;删除失败！&#39;.mysqli_error($conn));
}
//关闭连接
mysqli_close($conn);
?>

6. Select the database

Syntax:use database name;

Select the database in the php script:

<?php
//配置数据库信息
$localhost = &#39;localhost&#39;;
$username = &#39;zmz&#39;;
$password = &#39;20040315&#39;;

//建立到数据库的连接
$conn = mysqli_connect($localhost,$username,$password);
//检查连接
if(mysqli_connect_errno($conn)) {
die(&#39;连接失败！&#39;.mysqli_connect_error());
}
//选择数据库
$sel = mysqli_select_db($conn, &#39;zmz&#39;);
//var_dump($sel);
//die();
if(!$sel) {
die(&#39;选择失败！&#39;.mysqli_error($conn));
}
//关闭连接
mysqli_close($conn);
?>

The above are some database operations summarized for everyone, I hope they can help you. Thanks!

Recommended related tutorials: https://www.php.cn/php-weizijiaocheng-428689.html

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