如何为记账系统添加自定义报表功能 - 使用PHP开发自定义报表的方法

<?php
// 连接数据库
$conn = mysqli_connect("localhost", "username", "password", "database");

// 检查连接是否成功
if (!$conn) {
    die("连接数据库失败: " . mysqli_connect_error());
}

// 执行查询语句
$sql = "SELECT * FROM transactions";
$result = mysqli_query($conn, $sql);

// 输出查询结果
if (mysqli_num_rows($result) > 0) {
    while ($row = mysqli_fetch_assoc($result)) {
        echo "ID: " . $row["id"]. " - 金额: " . $row["amount"]. "<br>";
    }
} else {
    echo "0 结果";
}

// 关闭数据库连接
mysqli_close($conn);
?>

<form action="generate_report.php" method="post">
    <select name="report_type">
        <option value="income">收入报表</option>
        <option value="expense">支出报表</option>
        <option value="profit">利润报表</option>
    </select>
    <input type="submit" value="生成报表">
</form>

<?php
// 获取用户选择的报表类型
$report_type = $_POST["report_type"];

// 根据报表类型生成对应的SQL查询语句
if ($report_type == "income") {
    $sql = "SELECT SUM(amount) FROM transactions WHERE type = 'income'";
} elseif ($report_type == "expense") {
    $sql = "SELECT SUM(amount) FROM transactions WHERE type = 'expense'";
} elseif ($report_type == "profit") {
    $sql = "SELECT (SELECT SUM(amount) FROM transactions WHERE type = 'income') - (SELECT SUM(amount) FROM transactions WHERE type = 'expense')";
}

// 执行查询语句
$result = mysqli_query($conn, $sql);

// 输出查询结果
if (mysqli_num_rows($result) > 0) {
    while ($row = mysqli_fetch_assoc($result)) {
        echo "报表结果: " . $row["SUM(amount)"];
    }
} else {
    echo "0 结果";
}
?>