Query class

<?php
class Query{
  public $select;
  public $from;
  public $where;
  public $select_input = 'SELECT ';
  public $join_input = '';
  public $where_input = ' WHERE ';

  public $modified_cols = array('Location' => array('WarehouseLocation.Name AS Location', 'INNER JOIN WarehouseLocation ON Stockitem.Location = WarehouseLocation.Code'),
                         'Product' => array('Product.Name AS Product', 'INNER JOIN Product ON Stockitem.Product = Product.Code'),
                         'Manufacturer' => array('Manufacturer.Name AS Manufacturer', 'LEFT JOIN Manufacturer ON (Manufacturer = Manufacturer.Code)'),
                         'Model' => array('ProductModel.Name AS Model', 'LEFT JOIN ProductModel ON (ProductModel.Code = StockItem.Model)'),
                         'Customer' => array('Customer.Name as Customer', 'LEFT JOIN Customer ON (Customer.Code = StockItem.Customer)'),
                         'Status' => array('Status.Name AS Status', 'INNER JOIN Status ON Stockitem.Status = Status.Code'),
                         'Owner' => array('Owner.Name AS Owner', 'INNER JOIN Owner ON Stockitem.Owner = Owner.Code'),
                         'Condition' => array('Condition.Name AS Condition', 'INNER JOIN Condition ON Stockitem.Condition = Condition.Code')
                       );

  public function __construct($select, $from, $where){
    $this->select = $select;
    $this->from = $from;
    $this->where = $where;
  }

  public function try_this(){
    foreach($this->select as $s){
        if(isset($this->modified_cols[$s])){
            $this->select_input .= $this->modified_cols[$s][0] . ',';
            $this->join_input .= $this->modified_cols[$s][1] . ',';
        }else{
            $this->select_input .= $s . ','; }
    }
    $this->select_input = substr($this->select_input, 0, -1);
    $this->join_input = substr($this->join_input, 0, -1);
  }

  // public $count = sqlsrv_num_rows($this->output);
}

$q = new Query(array('Product', 'Model', 'ItemCode'), 'StockItem', 'Owner.Code=69');
// $q->query();
// print_r($q->select);
$q->try_this();
echo $q->join_input;

/**  $query_item_input = 'SELECT ItemCode, WarehouseLocation.Name AS Location, AuditDate, Product.Name AS Product,
                  Manufacturer.Name AS Manufacturer, ProductModel.Name AS Model, Customer.Name as Customer,
                  Status.Name AS Status, PCSerialNo, DisplayCode, BuyPrice, AuditCharge, FreightCharge,
                  MiscCharge, AvailableForSale, Owner.Name AS Owner, Condition.Name AS Condition

                  FROM StockItem

                  INNER JOIN Product ON Stockitem.Product = Product.Code
                  INNER JOIN Owner ON Stockitem.Owner = Owner.Code
                  INNER JOIN Status ON Stockitem.Status = Status.Code
                  INNER JOIN WarehouseLocation ON Stockitem.Location = WarehouseLocation.Code
                  INNER JOIN Condition ON Stockitem.Condition = Condition.Code
                  LEFT JOIN Manufacturer ON (Manufacturer = Manufacturer.Code)
                  LEFT JOIN ProductModel ON (ProductModel.Code = StockItem.Model)
                  LEFT JOIN Customer ON (Customer.Code = StockItem.Customer)

                  WHERE Owner.Code = ' . intval($_SESSION['company_id']) . $date_str . $sale_str . ';';

  // Executes the query
  $query_item_output = sqlsrv_query($conn, $query_item_input, array(), array( "Scrollable" => SQLSRV_CURSOR_KEYSET ));
  $row_count = sqlsrv_num_rows($query_item_output);
  $all_stock_arr = array();

  if ($query_item_output === false) {
    die(formatErrors(sqlsrv_errors()));
    echo 'Connection status: DOWN';}

  while( $row = sqlsrv_fetch_array( $query_item_output, SQLSRV_FETCH_ASSOC) ) {
    $all_stock_arr[] = $row;}

  sqlsrv_free_stmt($query_item_output);
  sqlsrv_close($conn);**/