如何利用PHP开发一个简单的客户关系管理系统

<?php
// 数据库连接信息
$hostname = "localhost";
$username = "root";
$password = "";
$dbname = "crm";

// 连接数据库
$conn = mysqli_connect($hostname, $username, $password, $dbname);

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

// 查询所有客户信息
$sql = "SELECT * FROM customers";
$result = mysqli_query($conn, $sql);

// 显示客户信息
echo "<h1>客户列表</h1>";
echo "<table>";
echo "<tr><th>姓名</th><th>邮箱</th><th>电话</th><th>地址</th><th>操作</th></tr>";
while ($row = mysqli_fetch_assoc($result)) {
  echo "<tr>";
  echo "<td>".$row['name']."</td>";
  echo "<td>".$row['email']."</td>";
  echo "<td>".$row['phone']."</td>";
  echo "<td>".$row['address']."</td>";
  echo "<td><a href='edit.php?id=".$row['id']."'>编辑</a> <a href='delete.php?id=".$row['id']."'>删除</a></td>";
  echo "</tr>";
}
echo "</table>";

// 关闭数据库连接
mysqli_close($conn);
?>

<?php
// 数据库连接信息
$hostname = "localhost";
$username = "root";
$password = "";
$dbname = "crm";

// 连接数据库
$conn = mysqli_connect($hostname, $username, $password, $dbname);

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

if ($_SERVER["REQUEST_METHOD"] == "POST") {
  // 获取表单提交的数据
  $name = $_POST['name'];
  $email = $_POST['email'];
  $phone = $_POST['phone'];
  $address = $_POST['address'];

  // 插入客户信息
  $sql = "INSERT INTO customers (name, email, phone, address) VALUES ('$name', '$email', '$phone', '$address')";
  
  if (mysqli_query($conn, $sql)) {
    echo "添加客户成功";
  } else {
    echo "添加客户失败: " . mysqli_error($conn);
  }
}

// 关闭数据库连接
mysqli_close($conn);
?>

<h1>添加客户</h1>
<form action="add.php" method="post">
  <label for="name">姓名:</label>
  <input type="text" name="name" required><br>

  <label for="email">邮箱:</label>
  <input type="email" name="email" required><br>

  <label for="phone">电话:</label>
  <input type="text" name="phone" required><br>

  <label for="address">地址:</label>
  <textarea name="address" required></textarea><br>

  <input type="submit" value="添加客户">
</form>

<?php
// 数据库连接信息
$hostname = "localhost";
$username = "root";
$password = "";
$dbname = "crm";

// 连接数据库
$conn = mysqli_connect($hostname, $username, $password, $dbname);

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

if ($_SERVER["REQUEST_METHOD"] == "POST") {
  // 获取表单提交的数据
  $id = $_POST['id'];
  $name = $_POST['name'];
  $email = $_POST['email'];
  $phone = $_POST['phone'];
  $address = $_POST['address'];

  // 更新客户信息
  $sql = "UPDATE customers SET name='$name', email='$email', phone='$phone', address='$address' WHERE id=$id";
  
  if (mysqli_query($conn, $sql)) {
    echo "编辑客户成功";
  } else {
    echo "编辑客户失败: " . mysqli_error($conn);
  }
} else {
  // 获取要编辑的客户信息
  $id = $_GET['id'];
  $sql = "SELECT * FROM customers WHERE id=$id";
  $result = mysqli_query($conn, $sql);
  $customer = mysqli_fetch_assoc($result);
}

// 关闭数据库连接
mysqli_close($conn);
?>

<h1>编辑客户</h1>
<form action="edit.php" method="post">
  <input type="hidden" name="id" value="<?php echo $customer['id']; ?>">

  <label for="name">姓名:</label>
  <input type="text" name="name" value="<?php echo $customer['name']; ?>" required><br>

  <label for="email">邮箱:</label>
  <input type="email" name="email" value="<?php echo $customer['email']; ?>" required><br>

  <label for="phone">电话:</label>
  <input type="text" name="phone" value="<?php echo $customer['phone']; ?>" required><br>

  <label for="address">地址:</label>
  <textarea name="address" required><?php echo $customer['address']; ?></textarea><br>

  <input type="submit" value="保存">
</form>