PHP PDO多个查询不会获得任何值

Question

I already did inner join before this code but then it seems like every time i have multiple queries it doesnt work. But then when I did it single query it seems fine and working. Please help me experts. Thank you!

<?php
include('db.php');
include('function.php');
if(isset($_POST["personal_info_id"]))
{
    $id1 = $_POST["personal_info_id"];
    $id2 = $_POST["personal_info_id"];
    $sql = "SELECT * FROM hr_details WHERE personal_info_id = '$id1'";
    $sql .="SELECT * FROM personal_info WHERE personal_info_id = '$id2'";
    $output = array();  
    $statement = $connection->prepare($sql);
    $statement->execute();
    $result = $statement->fetchAll();
    foreach($result as $row)
    {
        $output["firstname"] = $row["firstname"];
        $output["middlename"] = $row["middlename"];
        $output["lastname"] = $row["lastname"];
        $output["address"] = $row["address"];
        $output["birthdate"] = $row["birthdate"];
        $output["gender"] = $row["gender"];
        $output["religion"] = $row["religion"];
        $output["civil_status"] = $row["civil_status"];
        $output["biometrics"] = $row["biometrics"];
        if($row["image"] != '')
        {
        $output['user_image'] = '<img src="upload/'.$row["image"].'" class="img-thumbnail" width="50" height="35" /><input type="hidden" name="hidden_user_image" value="'.$row["image"].'" />';
        }
        else
        {
          $output['user_image'] = '<input type="hidden" name="hidden_user_image" value="" />';
         }

    }

    echo json_encode($output);

}
?>

Answer 1

Although it's possible to run multiple queries in one call with PDO, there is not a single reason to do so. Neither your case is an exception. It will never work as you think. Instead of stuffing several queries in one call like this, you need a single query with JOIN.

Another issue with your code is a cargo cult prepared statement. It looks like a real one but protects nothing. You should use parameters in your prepared query.

$sql = "SELECT * FROM hr_details hd, personal_info pi WHERE 
        hd.personal_info_id=pi.personal_info_id AND hd.personal_info_id=?";
$statement = $connection->prepare($sql);
$statement->execute([$_POST["personal_info_id"]]);
$result = $statement->fetchAll();