How to use php mysqli_num_fields function

php The mysqli_num_fields function is used to return the number of fields (columns) in the result set. Its syntax is mysqli_num_fields(result). The parameter result is required and refers to the result set identifier returned by mysqli_query(), mysqli_store_result() or mysqli_use_result(). .

php How to use the mysqli_num_fields function?

Definition and usage

mysqli_num_fields() function returns the number of fields (columns) in the result set.

Syntax

mysqli_num_fields(result);

Parameters

result Required. Specifies the result set identifier returned by mysqli_query(), mysqli_store_result(), or mysqli_use_result().

Return value: Returns the number of fields in the result set.

PHP version: 5

Return the number of fields (columns) in the result set:

<?php 
// 假定数据库用户名：root，密码：123456，数据库：RUNOOB 
$con=mysqli_connect("localhost","root","123456","RUNOOB"); 
if (mysqli_connect_errno($con)) 
{ 
    echo "连接 MySQL 失败: " . mysqli_connect_error(); 
} 
$sql = "SELECT name,url FROM websites ORDER BY alexa;";
if ($result=mysqli_query($con,$sql))
{
    // 返回结果集中的字段数
    $fieldcount=mysqli_num_fields($result);
    printf("结果集中有 %d 个字段。",$fieldcount);
    // 释放结果集
    mysqli_free_result($result);
}
mysqli_close($con);
?>

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