Datatable vyhledávání

<?php
/* Database connection start */
$servername = "";
$username = "";
$password = "";
$dbname = "";

$conn = mysqli_connect($servername, $username, $password, $dbname) or die("Connection failed: " . mysqli_connect_error());
mysqli_set_charset($conn,"utf8");





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

$columns = array(
 
    0 => 'datum',
    1 => 'cas',
    2 => 'poradatel',
    3 => 'misto',
    4 => 'akce'
);

// getting total number records without any search
$sql = "SELECT id, datum, cas, poradatel, misto, akce ";
$sql.=" FROM FOTOAS_akce2 ";
$query=mysqli_query($conn, $sql) or die("data.php: NACTENI MYSGL TABULKY RZH-SONGS-MY DO DATATABLE");
$totalData = mysqli_num_rows($query);
$totalFiltered = $totalData;  // when there is no search parameter then total number rows = total number filtered rows.

$sql = "SELECT id, datum, cas, poradatel, misto, akce ";
$sql.=" FROM FOTOAS_akce2 WHERE 1=1";
if( !empty($requestData['search']['value']) ) 
{   
    $sql.=" AND ( datum LIKE '".$requestData['search']['value']."%' ";
    
    
    
    
    $sql.=" OR cas LIKE '".$requestData['search']['value']."%' ";
    $sql.=" OR poradatel LIKE '".$requestData['search']['value']."%' ";
    $sql.=" OR misto LIKE '".$requestData['search']['value']."%' ";
    $sql.=" OR akce LIKE '".$requestData['search']['value']."%' )";
}


$query=mysqli_query($conn, $sql) or die("data.php: NACTENI MYSGL TABULKY ESHOP-OBJEDNAVKY DO DATATABLE");
$totalFiltered = mysqli_num_rows($query); // when there is a search parameter then we have to modify total number filtered rows as per search result. 
$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  */    
$query=mysqli_query($conn, $sql) or die("data.php: NACTENI MYSGL TABULKY ESHOP-OBJEDNAVKY DO DATATABLE");

$data = array();
while( $row=mysqli_fetch_array($query) ) 
{
$nestedData=array();
    
$nestedData[] = $row["datum"];
$nestedData[] = $row["cas"];
$nestedData[] = $row["poradatel"];
$nestedData[] = $row["misto"];
$nestedData[] = $row["akce"];

$nestedData[] = '<button class="btn btn-sm btn-success modal-eshop-edit" id="'.$row["id"].'" data-toggle="modal" data-target="#modal-eshop-edit" title="Editace"><i class="fa fa-edit" aria-hidden="true"></i></button>
<button class="btn btn-sm btn-danger" data-toggle="modal" data-target="#modal-eshop-delete" data-whatever="'.$row["id"].'" title="Smazat"><i class="fa fa-trash-o" aria-hidden="true"></i></button>';



$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
?>

$sql.=" OR cas LIKE '".mysqli_real_escape_string($conn,$requestData['search']['value'])."%' ";
$sql.=" OR poradatel LIKE '".mysqli_real_escape_string($conn,$requestData['search']['value'])."%' ";
$sql.=" OR misto LIKE '".mysqli_real_escape_string($conn,$requestData['search']['value'])."%' ";
$sql.=" OR akce LIKE '".mysqli_real_escape_string($conn,$requestData['search']['value'])."%') ";

$sql = "SELECT id, datum, cas, poradatel, misto, akce ";
$sql.=" FROM FOTOAS_akce2 ";

$sql = "SELECT id, datum, cas, poradatel, misto, akce ";
$sql.=" FROM FOTOAS_akce2 WHERE 1=1";

data.php: NACTENI MYSGL TABULKY ESHOP-OBJEDNAVKY DO DATATABLE error:Illegal mix of collations for operation 'like' sql:SELECT id, datum, cas, poradatel, misto, akce FROM FOTOAS_akce2 WHERE 1=1 AND ( datum LIKE 'Mě%' OR cas LIKE 'Mě%' OR poradatel LIKE 'Mě%' OR misto LIKE 'Mě%' OR akce LIKE 'Mě%')