PHP连接数据库

连接数据库有俩种方式

1、面向过程:

$link = mysqli_connect("localhost(本地地址)","数据库的账户","","数据库的名字");
if(mysqli_errno($link)){
echo mysqli_error($link);
}
//sql语句
$sql = "INSERT INTO users (username,age,pwd) VALUES ('王五',20,654321)";
//设置编码格式
//方式一：
//mysqli_query($link,"set names utf8");
//方式二
mysqli_set_charset($link, "utf8");
//执行sql
$res = mysqli_query($link, $sql);
if($res){
echo "添加成功";
}else{
echo "添加失败";
}

2、面向对象

$mysqli = new mysqli("localhost","root","","house");
if($mysqli->errno){
echo $mysqli->error;
}else{
echo "连接数据库成功";
}
$name = "马云";
$age  = 38;
$pwd = 123654;
$sql = "INSERT INTO users (username,age,pwd) VALUES ('".$name."',$age,$pwd)";
//echo $sql;die;
$reslut = add($sql);
if($reslut){
echo "添加成功";
}else{
echo "添加失败";
}

数据库的增删改查

下面都是我封装的函数…

1、添加
sql语句
举例:
$sql = “INSERT INTO users(username,pwd,age) VALUES (‘王林’,123123,45)”;

users在你数据库表的名字 username,pwd,age,在你数据库的字段,VALEUS 括号里是你要添加的内容;

function add($sql){
//连接数据库
$link = mysqli_connect("localhost","root","","house");
//设置编码格式
mysqli_query($link, "set names utf8");
$res = mysqli_query($link, $sql);

//    $reslut = mysqli_insert_id($link);
//    echo $reslut;die;
if($res){
    return true;    
}else{
    return false;
}
}

2、删除

$sql = “DELETE FROM users WHERE id=18”;

WHERE后面是你添加的条件为了更准确的去删除;

function delete($sql){
//连接数据库
$link = mysqli_connect("localhost","root","","house");
mysqli_query($link, "set names utf8");
$res = mysqli_query($link, $sql);
if($res){
    return true;    
}else{
    return false;
}
}    

3、更改
$sql = “UPDATE users SET username=’王’ WHERE id=18”;

function update($sql){
//连接数据库
$link = mysqli_connect("localhost","root","","house");
mysqli_query($link, "set names utf8");
$res = mysqli_query($link, $sql);
if($res){
    return true;    
}else{
    return false;
}
}

4、查询
$sql = “SELECT * FROM users”;

function getlist($sql){
//连接数据库
$link = mysqli_connect("localhost","root","","house");
//设置编码格式
mysqli_query($link, "set names utf8");
//执行sql
$res = mysqli_query($link, $sql);
//取所有数据
//    $list = mysqli_fetch_all($res);//常用
//    $arr = array();
//    while($list = mysqli_fetch_row($res)){
//        $arr[] = $list;
//    }
//常用
while($list = mysqli_fetch_assoc($res)){
    $arr[] = $list;
}

    return $arr;
}