update data in php

* Update data in the data table

* Note: Update is different from new addition. It is implemented based on query. Recommendation must also have update conditions

* Used Function:

* 1.mysqli_query(),

* 2.mysqli_errno(),mysqli_error(),

* 3.mysqli_affected_rows(),

* 4.mysqli_close()

//1. Connect to the database

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);

//2. Prepare the sql statement

$sql = "UPDATE staff SET salary=2900 WHERE staff_id=8";

//3. Execute the query: return true successfully , returns false on failure

if (mysqli_query($db, $sql)) {
    if (mysqli_affected_rows($db) > 0) {
        //返回受影响的记录数
        echo '成功的更新了'.mysqli_affected_rows($db).'条记录';
    } else {
        echo '没有记录被更新';
    }
} else {
    exit(mysqli_errno($db).':'.mysqli_error($db));
}

//4. Close the connection

mysqli_close($db);