SQL查询只能在phpmyAdmin中使用，而不能在php中使用

Question

如果我在phpMyAdmin中运行它（返回行），则此查询有效：

SELECT breweries.name AS brew_name,
       employees.f_name,
       employees.l_name,
       employees.age,
       employees.position,
       employees.pay_hr,
       beers.name AS fav_beer
  FROM employees
  INNER JOIN beers ON employees.beer_id = beers.id
  INNER JOIN breweries ON employees.brewery_id = breweries.id
  INNER JOIN locations ON breweries.location_id = locations.id
  WHERE locations.city = "San Diego"
    AND locations.state = "CA";

但是，当我通过表单获取用户输入并在城市/州/地区使用变量时，却没有结果：

$loc_str = $_GET["e_location"]; // Input is "San Diego, CA"
$loc_pieces = explode(",", $loc_str);
$city = $loc_pieces[0];
$state = $loc_pieces[1];

echo <<<res
  Showing all employees working at breweries in $city, $state.
res; //Correctly echos San Diego, CA

$query = <<<stmt
   SELECT breweries.name AS brew_name, employees.f_name, employees.l_name,
          employees.age, employees.position, employees.pay_hr,
          beers.name AS fav_beer
     FROM employees INNER JOIN beers ON employees.beer_id = beers.id
     INNER JOIN breweries ON employees.brewery_id = breweries.id
     INNER JOIN locations ON breweries.location_id = locations.id
     WHERE locations.city = "$city"
     AND locations.state = "$state";
stmt;
$stmt = $mysql->prepare($query);
$stmt->execute();
$stmt->bind_result($b_name, $f_name, $l_name, $age, $pos, $pay, $fav_beer);
while ( $stmt->fetch() ) {

  echo <<<res
    <tr>
      <td>$b_name</td>
      <td>$f_name, $l_name</td>
      <td>$age</td>
      <td>$pos</td>
      <td>$pay</td>
      <td>$fav_beer</td>
    </tr>

  res;
} // NO HTML OUTPUT

我究竟做错了什么？ 提前致谢。

Answer 1

eplode后你的状态仍然有空间。 在执行查询之前，对生成的分解零件使用trim ：

$city = trim($loc_pieces[0]);
$state = trim($loc_pieces[1]);

接着：

$query = <<<stmt
   SELECT breweries.name AS brew_name, employees.f_name, employees.l_name,
          employees.age, employees.position, employees.pay_hr,
          beers.name AS fav_beer
     FROM employees INNER JOIN beers ON employees.beer_id = beers.id
     INNER JOIN breweries ON employees.brewery_id = breweries.id
     INNER JOIN locations ON breweries.location_id = locations.id
     WHERE locations.city = ?
     AND locations.state = ? ;
stmt;
$stmt = $mysql->prepare($query);
$stmt->bind_param('ss', $city, $state);
$stmt->execute();