PHP MySQL Select Data

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PHP MySQL Select Data

The SELECT statement is used to select data from one or more tables: SELECT column_name(s) FROM table_name or we can use the * character to select ALL columns from a table: SELECT * FROM table_name

Then, the function num_rows() checks if there are more than zero rows returned. If there are more than zero rows returned, the function fetch_assoc() puts all the results into an associative array that we can loop through. The while() loop loops through the result set and outputs the data from the id, firstname and lastname columns.

Example (MySQLi Object-oriented)

    •       
                        <?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

$sql = "SELECT id, firstname, lastname FROM MyGuests";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    // output data of each row
    while($row = $result->fetch_assoc()) {
    echo "id: " . $row["id"]. " - Name: " .
     $row["firstname"]. " " . $row["lastname"]. "
    ";
    }
} else {
    echo "0 results";
}
$conn->close();
?>

    Example (MySQLi Procedural)

    ` 
    •       
                        <?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

// Create connection
$conn = mysqli_connect($servername, $username, $password, $dbname);
// Check connection
if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}

$sql = "SELECT id, firstname, lastname FROM MyGuests";
$result = mysqli_query($conn, $sql);

if (mysqli_num_rows($result) > 0) {
    // output data of each row
    while($row = mysqli_fetch_assoc($result)) {
    echo "id: " . $row["id"]. " - Name: " . $row["firstname"]. "
     " . $row["lastname"]. "
    ";
    }
} else {
    echo "0 results";
}

mysqli_close($conn);
?>

    Example (PDO)

    ` 
    •       
                        <?php
echo "<table style='border: solid 1px black;'>";
echo "<tr><th>Id</th><th>Firstname
</th><th>Lastname</th></tr>";

class TableRows extends RecursiveIteratorIterator {
    function __construct($it) {
    parent::__construct($it, self::LEAVES_ONLY);
    }

    function current() {
    return "<td style='width:150px;border:1px solid black;'>"
     . parent::current(). "</td>";
    }

    function beginChildren() {
    echo "<tr>";
    }

    function endChildren() {
    echo "</tr>" . "\n";
    }
}

$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDBPDO";

try {
    $conn = new PDO("mysql:host=$servername;dbname=$dbname", 
    $username, $password);
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $stmt = $conn->prepare("SELECT id, firstname, lastname FROM MyGuests");
    $stmt->execute();

    // set the resulting array to associative
    $result = $stmt->setFetchMode(PDO::FETCH_ASSOC);
    foreach(new TableRows(new RecursiveArrayIterator
    ($stmt->fetchAll())) as $k=>$v) {
    echo $v;
    }
} catch(PDOException $e) {
    echo "Error: " . $e->getMessage();
}
$conn = null;
echo ">/table>";
?>

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