为什么执行SELECT查询后，我的PDO $ stmt-> bind_result（）函数调用挂起？

Question

I have a MySQL database with table "Test" that has one column "TestData". There are three records with the following values for TestData: "This is value 1", "Here is another string", and "Third just for luck".

I wrote the following PHP code to retrieve the records.

<?php

try {
    $hostname = "redacted";
    $username = "redacted";
    $password = "redacted";
    $database = "redacted";

    $conn = new PDO("mysql: host=$hostname; dbname=$database", $username, $password);

    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    $sql = "SELECT TestData FROM Test";

    $stmt = $conn->prepare($sql);

    $stmt->execute();
}
catch(PDOException $e)
{
    $finalResult = $finalResult . "," . $e->getMessage();
}

echo "you are here (" . $stmt->rowCount() . ")<br>";

if ($stmt->rowCount() > 0) {

    echo "found (" . $stmt->rowCount() . ")<br>";

    $stmt->bind_result($td);

    echo "bind successful<br>";

    while ($stmt->fetch()) {
        echo "testdata (" . $td . ")<br>";
    }
} else {
    echo "nothing found<br>";
}

?>

The result I receive is

you are here (3)

found (3)

The PHP script never gets to the "echo 'bind successful
'" statement. The "$stmt->bind_result($td);" statement hangs.

The query appears to work, given that rowCount = 3. I've used essentially the same structure to perform INSERTS that work properly.

What's wrong with what I'm doing? Thanks.

Answer 1

I changed my code to the following and it works.

<?php

    $hostname = "redacted";
    $username = "redacted";
    $password = "redacted";
    $database = "redacted";

    $conn = new mysqli($hostname, $username, $password, $database);
    if ($conn->connect_error) {
        fwrite(STDERR, "Connection failed: " . $conn->connect_error . "\n");
        exit(1);
    }

    $sql = "SELECT TestData FROM Test WHERE ?";

    $stmt = $conn->stmt_init();

    if(!$stmt->prepare($sql)) {
        print "Failed to prepare statement\n";
    } else {
        $stmt->bind_param("s", $condition);
    }

    $condition = "1 = 1";

    $stmt->execute();
    $result = $stmt->get_result();
    while ($row = $result->fetch_array(MYSQLI_NUM)) {
        foreach ($row as $r) {    
            echo "testdata(" . $r . ")<br>";
        }
    }
?>

No more mixing PDO and MySQLi for me. Thanks for the help. Sorry for the inconvenience.

Answer 2

If you are just trying to get the items from the database using php pdo you need to store the results.

$results = $stmt->fetch(); //will get one row

$results = $stmt->fetchAll(); //will take all results and store in an array

hope this helps.