PHP mysqli_result $field_count 属性

 PHP MySQLi 函数

PHP mysqli_result::$field_count / mysqli_num_fields() 函数用于获取结果中的字段数量

语法

//面向对象风格
$mysqli_result->field_count;

//面向过程风格
mysqli_num_fields(result)

参数

返回值

返回一个表示字段数量的int。

示例:面向对象风格

下面的示例显示了mysqli_result的用法: :$field_count 属性。

<?php
//建立与数据库的连接
$mysqli = new mysqli("localhost", "user", "password", "database");
if ($mysqli->connect_errno) {
  echo "Failed to connect to MySQL: ". $mysqli->connect_error;
  exit();
}

//从数据库获取查询结果
$sql = "SELECT EmpID, Name, Age FROM Employee ORDER BY Age";
$result = $mysqli->query($sql);

//关闭连接
$mysqli->close();

//获取结果集中的字段数
$field_cnt = $result->field_count;

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

上述代码的输出将类似于:

Result set has 3 fields.

示例:面向过程风格

下面的示例显示了mysqli_num_fields()函数的用法。

<?php
//建立与数据库的连接
$mysqli = mysqli_connect("localhost", "user", "password", "database");
if (mysqli_connect_errno()) {
  echo "Failed to connect to MySQL: ". mysqli_connect_error();
  exit();
}

//从数据库获取查询结果
$sql = "SELECT EmpID, Name, Age FROM Employee ORDER BY Age";
$result = mysqli_query($mysqli, $sql);

//关闭连接
mysqli_close($mysqli);

//获取结果集中的字段数
$field_cnt = mysqli_num_fields($result);

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

上述代码的输出将类似于:

Result set has 3 fields.