从 MySQL 数据库读取数据
SELECT 语句用于从数据表中读取数据:
SELECT column_name(s) FROM table_name
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以下实例中我们从表 MyGuests 读取了 id, firstname 和 lastname 列的数据并显示在页面上：
实例 (MySQLi - 面向对象)
<?php
$servername = "localhost";
$username = "username";
$password =
"password";
$dbname =
"myDB";
// 创建连接
$conn = new mysqli($servername,
$username, $password, $dbname);
// 检测连接
if ($conn->connect_error)
{
die("连接失败: " . $conn->connect_error);
}
$sql = "SELECT id, firstname, lastname FROM MyGuests";
$result
= $conn->query($sql);
if ($result->num_rows > 0) {
// 输出每行数据
while($row = $result->fetch_assoc())
{
echo "<br> id: ".
$row["id"]. " - Name: ". $row["firstname"]. " " . $row["lastname"];
}
} else {
echo "0 个结果";
}
$conn->close();
?>以下实例读取了 MyGuests 表的所有记录并显示在 HTML 表格中：实例 (PDO)
<?php
echo "<table style='border: solid 1px black;'>";
echo "<tr><th>Id</th><th>Firstname</th><th>Lastname</th><th>Email</th><th>Reg
date</th></tr>";
class TableRows extends RecursiveIteratorIterator {
function __construct($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 * FROM MyGuests");
$stmt->execute();
// 设置结果集为关联数组
$result = $stmt->setFetchMode(PDO::FETCH_ASSOC);
foreach(new TableRows(new RecursiveArrayIterator($stmt->fetchAll())) as
$k=>$v) {
echo $v;
}
$dsn = null;
}
catch(PDOException
$e)
{
echo "Error: " . $e->getMessage();
}
$conn = null;
echo "</table>";
?>