Detailed introduction and examples of mysql operations (2)

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

Mysql is the most commonly used database management system.

Recommended mysql related video tutorials: https://www.php.cn/course/list/51/type/4.html

I will introduce it to you today Check out Mysql.

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

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. Create a data table

Syntax: create table table name (field 1, field 2...);

Use PHP script to create a data table:

<?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());
}
//创建数据表
$sql = "CREATE TABLE demo02(id SMALLINT(10) PRIMARY KEY,
age TINYINT(3),
name VARCHAR(10))CHARSET=utf8";
$query = mysqli_query($conn, $sql);
//判断是否创建成功
if(!$query) {
die(&#39;创建失败！&#39;.mysqli_error($conn));
}
//释放内存
mysqli_free_result($query);
//关闭连接
mysqli_close($conn);
?>

2. Delete the data table

Syntax: drop table table name;

Use PHP script to delete the data table:

<?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());
}
//删除数据表
$sql = "DROP TABLE runoob_tbl";
$query = mysqli_query($conn, $sql);
if(!$query) {
die(&#39;删除失败！&#39;.mysqli_error($conn));
}
//释放内存
mysqli_free_result($query);
//关闭连接
mysqli_close($conn);
?>

3. Insert data

Syntax: insert into table name (field 1, field 2 ...)values(value1,value2...);

Use PHP script to insert data:

<?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());
}
//插入数据
$sql = "INSERT INTO demo02(id,age,name)
VALUES(4,20,&#39;mm&#39;)";
$query = mysqli_query($conn,$sql);
//var_dump($query);
//die();
//判断是否插入成功
if(!$query) {
die(&#39;插入失败！&#39;.mysqli_error($conn));
}
//释放内存
mysqli_free_result($query);
//关闭连接
mysqli_close($conn);
?>

4. Query data

Syntax: select * from table;

Use PHP script to query data:

<?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);
//判断连接
if(mysqli_connect_errno($conn)) {
die(&#39;连接失败！&#39;.mysqli_connect_error());
}
//查询数据
$sql = "SELECT * FROM demo02";
$query = mysqli_query($conn, $sql);
//判断是否查询成功
if(!$query) {
die(&#39;查询失败！&#39;.mysqli_error($conn));
}
echo &#39;mysql查询语句&#39;;
echo &#39;<table border=1>&#39;;
echo &#39;<tr>
<td>id</td>
<td>age</td>
<td>name</td>
</tr>&#39;;
//循环数据
while($row = mysqli_fetch_assoc($query)) {
echo &#39;<tr>
<td>&#39;.$row[&#39;id&#39;].&#39;</td>
<td>&#39;.$row[&#39;age&#39;].&#39;</td>
<td>&#39;.$row[&#39;name&#39;].&#39;</td>
</tr>&#39;;
}
echo &#39;</table>&#39;;
//释放内存
mysqli_free_result($query);
//关闭连接
mysqli_close($conn);
?>

5, update statement

Syntax: update table name set field1 = new value;

Use PHP to update data

<?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());
}
//更新数据
$sql = "UPDATE demo02 SET name=&#39;zylmy&#39; WHERE id=1";
$query = mysqli_query($conn, $sql);
//var_dump($query);
//die();
//判断是否更新成功
if(!$query) {
die(&#39;更新失败！&#39;.mysqli_error($conn));
}
//关闭连接
mysqli_close($conn);
?>

The above are some basic operations about mysql compiled for you. I hope it will be useful to you. Everyone helps.

For more information, please pay attention to the relevant tutorials on the php Chinese website.

Recommended related articles: https://www.php.cn/php-weizijiaocheng-428722.html

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