PHP连接MySQL数据库并以json格式输出

<?php 
header("content-Type: text/html; charset=utf-8");//字符编码设置 
$servername = "localhost"; 
$username = "root"; 
$password = "123456"; 
$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 * FROM power WHERE DATE='2014-1-1'"; 
$result = $conn->query($sql); 
 
$arr = array(); 
// 输出每行数据 
while($row = $result->fetch_assoc()) { 
  $count=count($row);//不能在循环语句中，由于每次删除row数组长度都减小 
  for($i=0;$i<$count;$i++){ 
    unset($row[$i]);//删除冗余数据 
  } 
  array_push($arr,$row); 
 
} 
//print_r($arr); 
echo json_encode($arr,JSON_UNESCAPED_UNICODE);//json编码 
$conn->close(); 
 
?> 

<?php 
header("content-Type: text/html; charset=utf-8");//字符编码设置 
$servername = "localhost"; 
$username = "root"; 
$password = "123456"; 
$dbname = "mydb"; 
 
// 创建连接 
$con =mysqli_connect($servername, $username, $password, $dbname); 
// 检测连接 
if (mysqli_connect_errno()) 
{ 
  echo "Failed to connect to MySQL: " . mysqli_connect_error(); 
} 
 
$sql = "SELECT * FROM power WHERE DATE='2014-1-1'"; 
$result = mysqli_query($con,$sql); 
 
$arr = array(); 
while($row = mysqli_fetch_array($result)) { 
  $count=count($row);//不能在循环语句中，由于每次删除 row数组长度都减小 
  for($i=0;$i<$count;$i++){ 
    unset($row[$i]);//删除冗余数据 
  } 
 
  array_push($arr,$row); 
 
} 
echo json_encode($arr,JSON_UNESCAPED_UNICODE); 
mysqli_close($con); 
 
?> 

[{"NAME":"小区1","DM":"A","LNG":"564142.623","LAT":"4329376.169","DATE":"2014-1-1","VAL":"26.8"},{"NAME":"小区2","DM":"B","LNG":"563089.677","LAT":"4329311.017","DATE":"2014-1-1","VAL":"26.8"}] 

Array ( [0] => 小区1 [NAME] => 小区1 [1] => A [DM] => A [2] => 564142.623 [LNG] => 564142.623 [3] => 4329376.169 [LAT] => 4329376.169 [4] => 2014-1-1 [DATE] => 2014-1-1 [5] => 26.8 [VAL] => 26.8 )  

function encode_json($arr){ 
  $code = json_encode($arr); 
  return preg_replace("#\\\u([0-9a-f]+)#ie", "iconv('UCS-2', 'UTF-8', pack('H4', '\\1'))", $code); 
} 

function encode_json($str) { 
  return urldecode(json_encode(url_encode($str)));   
} 
 
/** 
 * 
 */ 
function url_encode($str) { 
  if(is_array($str)) { 
    foreach($str as $key=>$value) { 
      $str[urlencode($key)] = url_encode($value); 
    } 
  } else { 
    $str = urlencode($str); 
  } 
   
  return $str; 
} 

<!-- 面向过程的数据库mysqli连接 --> 
<?php 
  $conn=mysqli_connect("localhost","root","950609","user"); 
  // 连接数据库user 
  if (!$conn) { 
    # code...判断链接是否成功 
    echo "连接失败！"; 
    echo mysqli_connect_error(); 
    exit(); 
  } 
  mysqli_query($conn,"set names utf8"); 
  // 指定编码格式 
  $sql="select * from goods"; 
  // sql语句 
  $result=mysqli_query($conn,$sql); 
  // 执行sql语句，将执行结果返回到结果集中 
  $row=mysqli_fetch_array($result); 
  // 从结果集中取得一行作为数组 
  echo "<pre>"; 
  print_r($row); 
?> 

<!-- 面向对象的数据库mysqli连接 --> 
lt;?php 
$mysqli=new mysqli("localhost","root","950609","user"); 
if ( $mysqli -> connect_error ) { 
  die( 'Connect Error (' . $mysqli -> connect_errno . ') ' 
      . $mysqli -> connect_error ); 
} 
$sql = "select * from goods"; 
  $mysqli->set_charset("utf8");  
  $result = $mysqli->query($sql);  
  $row = $result->fetch_array(); // 从结果集中取得一行作为数组  
  echo '<pre>'; 
  print_r($row);  
  /* free result set */  
  $result->free();  
  /* close connection */  
  $mysqli->close();  
>