PHP表单将多个输入作为SQL查询发送

Question

I'm trying to create a PHP script that takes based on which input fields are filled in out of the total, uses those fields as SQL parameter to create a SQL query. But if none of the fields are filled out, then query would just retrieve all data.

Example: if fields "Name" and "City" are entered, then the query will have to concatenate "AND name = X_INPUT AND city = Y_INPUT" at the end.

I tried to instantiate $POST variables for the sake of testing but returns nothing. I'm not even sure if this is the best way to tackle the problem but any help would be greatly appreciated!

$_POST['name']="Linda";
$_POST['city']="";
$query = "select * from customers where gender = 'F'";

  if (empty($_POST)) {

     $query = "select * from customers where gender ='F'";
   }
  else{

     foreach($_POST as $key => $v) {
      if (!empty($_POST[$key])) {
          $cond = " and ".$key."='".$v."'";
          $query = $query.$cond;

Answer 1

The code:

$query = $query.$cond; 

every appends unnecessary query to the SQL. Get all your conditions in an array and simple concatenate them as a string. Everything should work this way.

$conditions = array();
foreach($POST as $key => $v) {
  if (!empty($_POST[$key])) {
    $conditions = " $key = '$v'";
  }
}
if (! empty($conditions)) {
    $sql .= implode(' AND ', $conditions);
}