PHP lengths / mysqli_fetch_lengths() 函数

定义和用法

lengths / mysqli_fetch_lengths() 函数返回结果集中当前行的字段长度。

实例

例子 1 - 面向对象风格

返回结果集中当前行的字段长度：

<?php
$mysqli = new mysqli("localhost","my_user","my_password","my_db");

if ($mysqli -> connect_errno) {
  echo "Failed to connect to MySQL: " . $mysqli -> connect_error;
  exit();
}

$sql = "SELECT * FROM Persons ORDER BY Lastname";

if ($result = $mysqli -> query($sql)) {
  $row = $result -> fetch_row();
  // 显示字段长度
  foreach ($result -> lengths as $i => $val) {
    printf("Field %2d has length: %2d\n", $i + 1, $val);
  }
  $result -> free_result();
}

$mysqli -> close();
?>

例子 2 - 过程式风格

返回结果集中当前行的字段长度：

<?php
$con = mysqli_connect("localhost","my_user","my_password","my_db");

if (mysqli_connect_errno()) {
  echo "Failed to connect to MySQL: " . mysqli_connect_error();
  exit();
}

$sql = "SELECT * FROM Persons ORDER BY Lastname";

if ($result = mysqli_query($con, $sql)) {
  $row = mysqli_fetch_row($result);
  // 显示字段长度
  foreach (mysqli_fetch_lengths($result) as $i => $val) {
    printf("Field %2d has length: %2d\n", $i+1, $val);
  }

  mysqli_free_result($result);
}

mysqli_close($con);
?>

语法

面向对象风格：

$mysqli_result -> lengths

过程式风格：

mysqli_fetch_lengths(result)

技术细节