PHP5中文手册

实例

返回结果集中字段（列）的数量：

 <?PHP
 $con=mysqli_connect("localhost","my_user","my_password","my_db");
 // Check connection
 if (mysqli_connect_errno($con))
 {
 echo "Failed to connect to MySQL: " . mysqli_connect_error();
 }

$sql="SELECT Lastname,Age FROM Persons ORDER BY Lastname";

if ($result=mysqli_query($con,$sql))
 {
 // Return the number of fields in result set
 $fieldcount=mysqli_num_fields($result);
 printf("Result set has %d fields.n",$fieldcount);
 // Free result set
 mysqli_free_result($result);
 }

mysqli_close($con);
 ?>