mysqli_result::fetch_field_direct

定义和用法

fetch_field_direct() / mysqli_fetch_field_direct() 函数返回结果集中单个字段的元数据，作为一个对象。

实例

例子 1 - 面向对象风格

返回结果集中单个字段的元数据，然后打印字段的名称、表和最大长度：

<?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 Lastname, Age FROM Persons ORDER BY Lastname";

if ($result = $mysqli -> query($sql)) {

  // 获取列 "Age" 的字段信息
  $fieldinfo = $result -> fetch_field_direct(1);

  printf("Name: %s\n", $fieldinfo -> name);
  printf("Table: %s\n", $fieldinfo -> table);
  printf("Max. Len: %d\n", $fieldinfo -> max_length);
  $result -> free_result();
}

$mysqli -> close();
?>

例子 2 - 过程式风格

返回结果集中单个字段的元数据，然后打印字段的名称、表和最大长度：

<?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 Lastname, Age FROM Persons ORDER BY Lastname";

if ($result = mysqli_query($con, $sql)) {

  // 获取列 "Age" 的字段信息
  $fieldinfo = mysqli_fetch_field_direct($result, 1);

  printf("Name: %s\n", $fieldinfo -> name);
  printf("Table: %s\n", $fieldinfo -> table);
  printf("Max. Len: %d\n", $fieldinfo -> max_length);

  mysqli_free_result($result);
}

mysqli_close($con);
?>