学习 :PHP MYSQL 读取数据库

学习PHP MYSQL笔记

<?php 
$dbhost="localhost"; //数据库地址
$db_name="root"; //用户名
$db_pas=""; //密码
$db_user="user"; //数据库
$conn=mysqli_connect($dbhost,$db_name,$db_pas,$db_user); //链接数据库

mysqli_query($conn , "set names utf8"); //设置utf8

$sql = 'SELECT *  FROM test WHERE status=1'; 
mysqli_select_db( $conn, 'XL' );	
$retval = mysqli_query( $conn, $sql );
				
if(!$retval )
{
	die('无法读取数据: ' . mysqli_error($conn));
}
 //输出数据
while($row = mysqli_fetch_array($retval, MYSQLI_ASSOC))
{
	$id= ($row['id']);
	$name=($row['username']);
	$wechat=($row['wechat']);
	$tel=($row['tel']);
	echo  "序号:$id <br/>姓名:$name <br/>微信:$wechat <br/>电话:$tel<br/>";
}
mysqli_close($conn); 

?>

读取tel,8,4 从第八位开始一共4位数 ：如读取手机号后四位，

也可以理解8代表从左边开始第八位，4代表读取几个字符

SELECT SUBSTRING(tel,8,11) FROM `test`

从左边开始前4为

SELECT LEFT(tel,4) FROM `test`

从右边开始后4为

SELECT RIGHT(tel,4) FROM `test`

关键词搜索POST

<?php
//配置数据库信息
$db_host = "localhost"; //主机名
$db_port = "3306"; //端口
$db_user = "root"; //用户名
$db_pass = ""; //用户密码
$db_name = "word"; //数据库名
$charset = "utf8"; //编码
//连接数据库
if(!$conn = @mysqli_connect($db_host.":".$db_port,$db_user,$db_pass,$db_name)){
    echo "<h2>PHP连接Mysql服务器失败</h2>";
    echo mysqli_connect_error();
    die ();
}
//选择数据库
if(!mysqli_select_db($conn,$db_name)){
    echo "<h2>选择数据库{$db_name}失败</h2>";
    die ();
}
//设置返回数据库字节编码
mysqli_set_charset($conn,$charset);

//$keywords = $_POST['keywords']; //关键词获取
$keywords = isset($_POST['keywords'])?$_POST['keywords']:'';
$sql = 'SELECT *  FROM test WHERE status=1 AND (name LIKE "%'.$keywords.'%" OR brand LIKE "%'.$keywords.'%" OR spec LIKE "%'.$keywords.'%") ORDER BY id DESC';
$result = mysqli_query($conn,$sql); //发送一条Mysql查询 （连接数据库，查询语句）
$arrs = mysqli_fetch_all($result,MYSQLI_ASSOC); //获取所有行数据
//$records = mysqli_num_rows($result);//获取返回数据行数
?>