fetch_lengths

❮ PHP MySQLi 参考手册

示例 - 面向对象的样式

返回结果集中的字段长度:

<?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 = $result -> fetch_row();
  // Display field lengths
  foreach ($result -> lengths as $i => $val) {
    printf("Field %2d has length: %2d\n", $i + 1, $val);
  }
  $result -> free_result();
}

$mysqli -> close();
?>

查看底部的程序样式示例。

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定义和用法

lengths / mysqli_fetch_lengths() 函数返回结果集中的字段长度。

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语法

面向对象的风格:

$mysqli_result -> lengths

程序风格:

mysqli_fetch_lengths(result)

参数值

参数	描述
result	必需。规定由 mysqli_query()、mysqli_store_result() 或 mysqli_use_result() 返回的结果集标识符。

技术细节

返回值:	如果整数表示每个字段（列）的长度则返回数组，如果发生错误则返回 FALSE。
PHP 版本:	5+

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示例 - 程序样式

返回结果集中的字段长度:

<?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);
  // Display field lengths
  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);
?>

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❮ PHP MySQLi 参考手册