数据表 + 服务器端处理 + 搜索筛选

我正在遵循本教程：
http://coderexample.com/datatable-demo-server-side-in-phpmysql-and-ajax/

这是演示：
http://coderexample.com/demo/datatable-demo-server-side-in-phpmysql-and-ajax/

如果我在搜索输入中搜索ou，我会得到No matching records found但我希望返回的是至少Airi Satou这一行。

我认为这是我必须更改的代码，因为我必须做搜索服务器端。

<?php
/* Database connection start */
$servername = "localhost";
$username = "root";
$password = "Password1";
$dbname = "test";
$conn = mysqli_connect($servername, $username, $password, $dbname) or die("Connection failed: " . mysqli_connect_error());
/* Database connection end */

// storing  request (ie, get/post) global array to a variable  
$requestData= $_REQUEST;

$columns = array( 
// datatable column index  => database column name
    0 =>'employee_name', 
    1 => 'employee_salary',
    2=> 'employee_age'
);
// getting total number records without any search
$sql = "SELECT employee_name, employee_salary, employee_age ";
$sql.=" FROM employee";
$query=mysqli_query($conn, $sql) or die("employee-grid-data.php: get employees");
$totalData = mysqli_num_rows($query);
$totalFiltered = $totalData;  // when there is no search parameter then total number rows = total number filtered rows.

if( !empty($requestData['search']['value']) ) {
    // if there is a search parameter
    $sql = "SELECT employee_name, employee_salary, employee_age ";
    $sql.=" FROM employee";
    $sql.=" WHERE employee_name LIKE '".$requestData['search']['value']."%' ";    // $requestData['search']['value'] contains search parameter
    $sql.=" OR employee_salary LIKE '".$requestData['search']['value']."%' ";
    $sql.=" OR employee_age LIKE '".$requestData['search']['value']."%' ";
    $query=mysqli_query($conn, $sql) or die("employee-grid-data.php: get employees");
    $totalFiltered = mysqli_num_rows($query); // when there is a search parameter then we have to modify total number filtered rows as per search result without limit in the query 
    $sql.=" ORDER BY ". $columns[$requestData['order'][0]['column']]."   ".$requestData['order'][0]['dir']."   LIMIT ".$requestData['start']." ,".$requestData['length']."   "; // $requestData['order'][0]['column'] contains colmun index, $requestData['order'][0]['dir'] contains order such as asc/desc , $requestData['start'] contains start row number ,$requestData['length'] contains limit length.
    $query=mysqli_query($conn, $sql) or die("employee-grid-data.php: get employees"); // again run query with limit
} else {    
    $sql = "SELECT employee_name, employee_salary, employee_age ";
    $sql.=" FROM employee";
    $sql.=" ORDER BY ". $columns[$requestData['order'][0]['column']]."   ".$requestData['order'][0]['dir']."   LIMIT ".$requestData['start']." ,".$requestData['length']."   ";
    $query=mysqli_query($conn, $sql) or die("employee-grid-data.php: get employees");
}
$data = array();
while( $row=mysqli_fetch_array($query) ) {  // preparing an array
    $nestedData=array(); 
    $nestedData[] = $row["employee_name"];
    $nestedData[] = $row["employee_salary"];
    $nestedData[] = $row["employee_age"];
    $data[] = $nestedData;
}

$json_data = array(
            "draw"            => intval( $requestData['draw'] ),   // for every request/draw by clientside , they send a number as a parameter, when they recieve a response/data they first check the draw number, so we are sending same number in draw. 
            "recordsTotal"    => intval( $totalData ),  // total number of records
            "recordsFiltered" => intval( $totalFiltered ), // total number of records after searching, if there is no searching then totalFiltered = totalData
            "data"            => $data   // total data array
            );
echo json_encode($json_data);  // send data as json format
?>

我说这是我必须更改的代码是对的吗？
如果是这样，谁能告诉我必须做什么？
我知道这有很多问题要问，但希望得到指导！