(PHP 5, PHP 7, PHP 8, PECL OCI8 >= 1.1.0)
oci_field_is_null — Checks if a field in the currently fetched row is null
$statement, string|int $column): bool
   Checks if the given column from the current row of
   statement is null. 
  
statementA valid OCI statement identifier.
columnCan be the field's index (1-based) or name.
   Returns true if column is null, false otherwise. 
  
Example #1 oci_field_name() example
<?php
// Create the table with:
//   CREATE TABLE mytab (c1 NUMBER);
//   INSERT INTO mytab VALUES (1);
//   INSERT INTO mytab VALUES (NULL);
$conn = oci_connect("hr", "hrpwd", "localhost/XE");
if (!$conn) {
    $m = oci_error();
    trigger_error(htmlentities($m['message']), E_USER_ERROR);
}
$stid = oci_parse($conn, "SELECT * FROM mytab");
oci_execute($stid);
while (($row = oci_fetch_array($stid, OCI_RETURN_NULLS)) != false) {
    $ncols = oci_num_fields($stid);
    for ($col = 1; $col <= $ncols; $col++) {
        var_dump(oci_field_is_null($stid, $col));
    }    
}
// Outputs:
//    bool(false)
//    bool(true)
oci_free_statement($stid);
oci_close($conn);
?>
Note:
In PHP versions before 5.0.0 you must use ocicolumnisnull() instead. This name still can be used, it was left as alias of oci_field_is_null() for downwards compatability. This, however, is deprecated and not recommended.