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Question

这是一个基本的数据表小提琴

这是一个基本数据表小提琴与lengthMenu

我要做的是在我的服务器端处理示例中进行此操作。

我可以对我的index.php文件执行以下操作，以使下拉菜单正确显示。

$(document).ready(function() {
  var dataTable = $('#employee-grid').DataTable({
    "lengthMenu": [
      [10, 25, 50, -1],
      [10, 25, 50, "All"]
    ],
    "processing": true,
    "serverSide": true,
    "ajax": {
      url: "employee-grid-data.php", // json datasource
      type: "post", // method  , by default get
      error: function() { // error handling
        $(".employee-grid-error").html("");
        $("#employee-grid").append('<tbody class="employee-grid-error"><tr><th colspan="3">No data found in the server</th></tr></tbody>');
        $("#employee-grid_processing").css("display", "none");

      }
    }
  });
});

所以，如果我选择工作好10 ， 25或50 ，但如果我选择All我得到No data found in the server 。 所以我的问题在我的employee-grid-data.php文件中， 在这里注意到，这就是我遇到的困难。 我需要执行一条if语句来处理此All选项或-1因为这是我在$requestData['length']选择All时传递给服务器的内容

我已经确定了我使用$requestData['length']的两个区域，我相信这是一个问题。

$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

因此，我要做的是尝试编写以下代码：
如果$requestData['length']不等于-1
做这条线
其他
在不使用$requestData['length']作为参数的情况下执行此行。

这就是我遇到的困难。

这是我的尝试，但这可能是语法问题或其他问题。 我不太擅长调试此程序。

if ($requestData['length']!==-1){
    $sql.=" ORDER BY ". $columns[$requestData['order'][0]['column']]."   ".$requestData['order'][0]['dir']."   LIMIT ".$requestData['start']." ,".$requestData['length']."   ";
} else {
    $sql.=" ORDER BY ". $columns[$requestData['order'][0]['column']]."   ".$requestData['order'][0]['dir']
}
$query=mysqli_query($conn, $sql) or die("employee-grid-data.php: get employees");

当我访问index.php页面时No data found in the server和控制台中index.php找到No data found in the server 500 (Internal Server Error) 。

谁能告诉我我的代码应该是什么样？ 或者我该如何调试呢？

理想情况下，我希望能够添加一个基本的if else语句，只是看我是否可以单独解决这一问题，但是不确定如何在此设置中执行此操作。 使用Javasecript，我通常会使用console.log

这是我的整个employee-grid-data.php文件供参考：

<?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 

    if ($requestData['length']!==-1){   
        $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.
    } else {
        $sql.=" ORDER BY ". $columns[$requestData['order'][0]['column']]."   ".$requestData['order'][0]['dir']
    }
    $query=mysqli_query($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";

    if ($requestData['length']!==-1){
        $sql.=" ORDER BY ". $columns[$requestData['order'][0]['column']]."   ".$requestData['order'][0]['dir']."   LIMIT ".$requestData['start']." ,".$requestData['length']."   ";
    } else {
        $sql.=" ORDER BY ". $columns[$requestData['order'][0]['column']]."   ".$requestData['order'][0]['dir']
    }
    $query=mysqli_query($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

?>

edit1测试http://phpfiddle.org/的好链接

Answer 1

这是我必须添加以处理等于-1的$requestData['length']的代码。 我必须在有$requestData['length']地方添加。 这是我能做的最好的。

if ($requestData['length'] > 0 ){
    $sql.=" ORDER BY ". $columns[$requestData['order'][0]['column']]."   ".$requestData['order'][0]['dir']."   LIMIT ".$requestData['start']." ,".$requestData['length']."   ";
} else {
    $sql.=" ORDER BY ". $columns[$requestData['order'][0]['column']]."   ".$requestData['order'][0]['dir']."   ";
}