php数据库增删改查代码

以下是一个简单的 PHP 数据库增删改查的示例代码：

连接数据库：

$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database_name";

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

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

添加数据：

$sql = "INSERT INTO table_name (column1, column2, column3) VALUES ('value1', 'value2', 'value3')";

if ($conn->query($sql) === TRUE) {
  echo "数据添加成功";
} else {
  echo "添加数据失败: " . $conn->error;
}

更新数据：

$sql = "UPDATE table_name SET column1='new_value' WHERE id=1";

if ($conn->query($sql) === TRUE) {
  echo "数据更新成功";
} else {
  echo "更新数据失败: " . $conn->error;
}

删除数据：

$sql = "DELETE FROM table_name WHERE id=1";

if ($conn->query($sql) === TRUE) {
  echo "数据删除成功";
} else {
  echo "删除数据失败: " . $conn->error;
}

查询数据：

$sql = "SELECT * FROM table_name";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
  // 输出数据
  while($row = $result->fetch_assoc()) {
    echo "id: " . $row["id"]. " - column1: " . $row["column1"]. " - column2: " . $row["column2"]. "<br>";
  }
} else {
  echo "0 结果";
}

关闭连接：

$conn->close();