PHP MySQL 读取数据
当 PHP 连接到 MySQL 数据库后，需要向数据库读取数据？那么怎么读取呢？一起来看看。
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
如需学习更多关于 SQL 的知识，请访问我们的 SQL 教程。
---
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("Connection failed: " . $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 "
id: ". $row["id"]. " - Name: ". $row["firstname"]. " " . $row["lastname"];
}
} else {
echo "0 results";
}
$conn->close();
?>
以下实例读取了 MyGuests 表的所有记录并显示在 HTML 表格中：
实例 (PDO)
----
<?php
echo "
";
echo "| Id | Firstname | Lastname | Email | Reg date |
|---|
";
class TableRows extends RecursiveIteratorIterator {
function construct($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>" . "
";
}
}
$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 "
";
?>
```