前端了解的mysql语句

1.登录mysql，链接mysql，选择数据库
$link = @new mysqli("localhost:3306","root","root","test1910"); if($link->connect_error){
echo $link->connect_error;
}

2.向mysql发送命令，根据命令执行不同的功能
$link->query("mysql命令");

增
$str = "INSERT stu (name,tel,cj) VALUES('李四','345',78.5)";
$q = $link->query($str);
if($q){
    echo "insert success";
}else{
    echo "insert error";
}

改
$str = "UPDATE stu SET name='王二' WHERE id=5";
$q = $link->query($str);
if($q){
    echo "update success";
}else{
    echo "update error";
}

删
$str = "DELETE FROM stu WHERE id=6";
$q = $link->query($str);
if($q){
    echo "delete success";
}else{
    echo "delete error";
}

查：资源型数据
$str = "SELECT * FROM stu";
$q = $link->query($str);
if($q){

    echo $q;

}else{
    echo "select error";
}