The mysqli_num_fields() function is used to display the number of fields in a result set. In other words, you can say that it returns the number of columns that is coming from a select query.

Syntax:

mysqli_num_fields(result);

In above syntax, there is only one parameter which is required parameter. It specify the result set. This function returns the number of fields in the result set.

For example:

<?php
$con=mysqli_connect("localhost","mysqlusername","mysqlpassword","dbname");
// Check connection
if (mysqli_connect_errno())
  {
  echo "Failed to connect to MySQL: " . mysqli_connect_error();
  }

$sql="SELECT * FROM tablename";

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);
?>

The above example return the number of fields in the result set returned by the function mysqli_query().