mysql_num_fields

Function name: mysql_num_fields()

Applicable version: PHP 4, PHP 5, PHP 7

Usage: The mysql_num_fields() function is used to get the number of fields in the result set.

Syntax: int mysql_num_fields ( resource $result )

parameter:

• result: Required. A MySQL result set identifier returned by mysql_query(), mysql_store_result(), or mysql_use_result().

Return value: Returns the number of fields in the result set, and if the result set is empty or an error occurs, return 0.

Example:

 <?php // 建立与MySQL 数据库的连接$conn = mysql_connect("localhost", "username", "password"); if (!$conn) { die("连接失败: " . mysql_error()); } // 选择数据库mysql_select_db("mydb", $conn); // 执行查询$result = mysql_query("SELECT * FROM users", $conn); // 获取结果集中字段的数量$numFields = mysql_num_fields($result); echo "结果集中的字段数量为：" . $numFields; // 关闭连接mysql_close($conn); ?>

In the above example, we first establish a connection to the MySQL database and then select the database to operate on. Next, we execute a SELECT query statement and store the result in the $result variable. Finally, we use mysql_num_fields() function to get the number of fields in the result set and output it to the browser.

Please note that since PHP 7 has abandoned the mysql_ function, it is recommended to use the mysqli or PDO extension instead.