我有一个php，我需要很多选择，比如10个，所以我做了：

$stmt = $mysqli_->prepare("SELECT count(id) as num FROM table WHERE id=?");
$stmt->bind_param('i', $id);
$stmt->execute();
$stmt->bind_result($count);
$stmt->fetch();
$stmt->close();

$stmt = $mysqli_->prepare("SELECT count(id) as num FROM table2 WHERE id=?");
$stmt->bind_param('i', $id);
$stmt->execute();
$stmt->bind_result($count2);
$stmt->fetch();
$stmt->close();

$stmt = $mysqli_->prepare("SELECT count(id) as num FROM table3 WHERE id=?");
$stmt->bind_param('i', $id);
$stmt->execute();
$stmt->bind_result($count3);
$stmt->fetch();
$stmt->close();

...

用这个可以吗 $stmt->close(); 一直这样还是会影响连接性能？