PHP类中的SELECT查询

SELECT column1, column2, ...
FROM table_name
WHERE condition;

<?php
$servername = "数据库服务器名";
$username = "用户名";
$password = "密码";
$dbname = "数据库名";

// 创建连接
$conn = new mysqli($servername, $username, $password, $dbname);

// 检查连接是否成功
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}

// 构造SELECT查询语句
$sql = "SELECT column1, column2 FROM table_name WHERE condition";

// 执行查询
$result = $conn->query($sql);

// 检查查询结果
if ($result->num_rows > 0) {
    // 输出每行数据
    while($row = $result->fetch_assoc()) {
        echo "column1: " . $row["column1"]. " - column2: " . $row["column2"]. "<br>";
    }
} else {
    echo "0 结果";
}

// 关闭连接
$conn->close();
?>