php mysqli_num_fields()函数

定义

mysqli_num_fields()函数返回结果集中的字段（列）数。

语法

PHP mysqli_num_fields()函数具有以下语法。

面向对象的风格：

int $mysqli_result->field_count;

程序风格：

int mysqli_num_fields ( mysqli_result $result )

参数

返回值

结果集中的字段数。

实例

以下代码返回结果集中的列数。

<?php
//  http://www.manongjc.com/article/1685.html
//  作者：码农教程
$con=mysqli_connect(\"localhost\",\"my_user\",\"my_password\",\"my_db\");
if (mysqli_connect_errno($con)){
  echo \"Failed to connect to MySQL: \" . mysqli_connect_error();
}

$sql=\"SELECT name FROM emp\";

if ($result=mysqli_query($con,$sql)){
  // Return the number of fields in result set
  $fieldcount=mysqli_num_fields($result);

  print $fieldcount;

  mysqli_free_result($result);
}

mysqli_close($con);
?>

实例2

<?php
//  http://www.manongjc.com/article/1685.html
//  作者：码农教程
$mysqli = new mysqli(\"localhost\", \"my_user\", \"my_password\", \"world\");

if (mysqli_connect_errno()) {
    printf(\"Connect failed: %s\\n\", mysqli_connect_error());
    exit();
}

if ($result = $mysqli->query(\"SELECT * FROM City\")) {

    /* determine number of fields in result set */
    $field_cnt = $result->field_count;

    printf(\"Result set has %d fields.\\n\", $field_cnt);

    $result->close();
}

$mysqli->close();
?>