php向数据表新增数据

define ('DB_HOST', 'localhost');
define ('DB_USER', 'root');
define ('DB_PASS', 'root');
define ('DB_NAME', 'php');
define ('DB_CHAR', 'utf8');
$db = @mysqli_connect(DB_HOST, DB_USER, DB_PASS);
if (mysqli_connect_errno($db)) {
    exit('连接失败'.mysqli_connect_error($db));
}
mysqli_select_db($db, DB_NAME);
mysqli_set_charset($db, DB_CHAR);

$sql = "INSERT INTO staff (staff_id,name,sex,age,salary) VALUES (null,'赵敏',1,30,4000)";

$sql = "INSERT  staff (name,sex,age,salary) VALUES ('小昭',1,20,2400),('宋青书',0,40,1800),('成昆',0,70,9000)";

$sql = "INSERT staff SET name='灭绝师太',sex=1, age=58, salary=9999";

$res = mysqli_query($db, $sql);
var_dump($res);exit;
if (mysqli_query($db, $sql)) {
    if (mysqli_affected_rows($db) > 0) {
        //返回受影响的记录数与新增主键id
        echo '成功的新增了'.mysqli_affected_rows($db).'条记录,<br>新记录的主键id是:'.mysqli_insert_id($db);
    } else {
        echo '没有记录被新增';
    }
} else { //项目上线后,不应该将出错信息显示出来,否则会暴露数据库的相关信息
    exit(mysqli_errno($db).':'.mysqli_error($db));
}

mysqli_close($db);